Parotitis
Inflammation of the parotid gland, most commonly caused by viral infection (such as mumps) or bacterial infection due to salivary stasis, presenting with painful swelling over the angle of the jaw.
Parotitis
Parotitis literally breaks down as "parotid" + "-itis" → inflammation of the parotid gland. The parotid gland itself gets its name from Greek: para- (beside) + ous/otos (ear) — the gland that sits beside the ear.
Parotitis refers to inflammation of the parotid gland, which may be caused by infection (bacterial or viral), autoimmune disease, obstruction, or systemic conditions. In clinical practice, the term most commonly refers to either:
- Acute suppurative (bacterial) parotitis — a potentially serious infection seen in debilitated, dehydrated, post-operative, or elderly patients
- Viral parotitis — classically caused by mumps, presenting as bilateral painless-to-mildly-tender swelling
Why the parotid gland specifically? The parotid is the largest salivary gland and has a long duct (Stensen's duct) that opens into the oral cavity — a non-sterile environment. Any condition that reduces salivary flow allows oral bacteria to migrate retrogradely up the duct into the gland. The parotid's serous (watery, low-mucin) secretion also lacks the protective mucin-rich, lysozyme-dense properties of submandibular secretions, making it relatively more vulnerable to ascending infection [1][2].
Epidemiology
- Most common in elderly, debilitated, post-operative, or immunocompromised patients
- Historically a dreaded post-surgical complication (before modern IV fluid resuscitation) — mortality was historically very high in the pre-antibiotic era
- Incidence has decreased with improved perioperative hydration and oral hygiene practices
- No strong sex predilection for suppurative parotitis specifically (contrast with sialolithiasis which has female predominance)
- Mumps is the commonest cause of viral parotitis [3]
- Before widespread vaccination, mumps was a common childhood illness (peak age 5–9 years)
- In Hong Kong, MMR (Measles-Mumps-Rubella) vaccination is part of the Childhood Immunisation Programme — given at 1 year and Primary 1 (age 6). As a result, mumps incidence in HK has dropped dramatically
- Sporadic outbreaks still occur in unvaccinated or under-vaccinated populations, including young adults in institutional settings (university dormitories, military barracks)
- Increased incidence of benign lymphoepithelial cysts and diffuse infiltrative lymphocytosis syndrome (DILS) causing bilateral parotid enlargement in HIV patients — particularly seen in the pre-HAART era [2]
Understanding risk factors requires understanding the pathophysiology — anything that reduces salivary flow or introduces organisms into the gland predisposes to parotitis.
| Risk Factor | Mechanism |
|---|---|
| Dehydration (post-operative, elderly, critically ill) | Reduced salivary production → stasis → retrograde bacterial colonization [1] |
| Debilitation / infirm elderly | Poor oral hygiene + reduced oral intake → bacterial overgrowth + reduced salivary flow [1] |
| Salivary duct obstruction (calculi/sialolithiasis) | Physical obstruction → stasis proximal to stone → retrograde infection [2] |
| Tumour of the oral cavity | Extrinsic compression of Stensen's duct → obstruction → stasis [2] |
| Post-operative / intubated patients | Dehydration + NPO status + endotracheal tube reduces oral clearance + anticholinergic anaesthetic agents [2] |
| Anticholinergic drugs (atropine, glycopyrrolate, antihistamines, tricyclics) | Block muscarinic M3 receptors on salivary acinar cells → ↓ salivary flow [2] |
| Recent intensive teeth cleaning | Transient bacteraemia + mechanical trauma to duct orifice [2] |
| Poor oral hygiene | Increased bacterial load in oral cavity → greater risk of retrograde seeding |
| Immunosuppression (HIV, chemotherapy, diabetes mellitus) | Impaired local and systemic immune defences |
| Sjögren's syndrome | Chronic lymphocytic infiltration of salivary glands → reduced flow → recurrent sialadenitis |
| Radiation to head & neck | Radiation-induced fibrosis and atrophy of salivary acini → xerostomia (dry mouth) → stasis |
Post-Operative Parotitis
Think of the classic scenario: an elderly patient, 2–3 days post-abdominal surgery, NPO, on IV fluids (often under-hydrated), receiving anticholinergic premedication. They develop a unilateral painful swelling anterior to the ear with purulent discharge from Stensen's duct. This is the textbook presentation of acute suppurative parotitis.
Anatomy and Function
The parotid gland is the largest of the three paired major salivary glands (parotid, submandibular, sublingual). Understanding its anatomy is critical because of the structures that run through it.
Location [2]:
- Anterior to the external auditory canal
- Superior to the angle of the mandible
- Inferior to the zygomatic arch
- Majority is superficial to the masseter muscle
- The gland wraps around the posterior border of the ramus of the mandible
Lobes:
- The parotid is divided into a superficial lobe (80%) and a deep lobe (20%) by the facial nerve (CN VII), which passes through the substance of the gland
- Differentiation between superficial and deep lobe:
- Imaginary line from mandible to mastoid tip (above = superficial; below = deep)
- Retromandibular vein (above = superficial; below = deep) [2]
Key structures traversing/within the parotid gland (from superficial to deep — mnemonic: "SaVaNA" = Superficial to deep: Skin → Vein → Artery → Nerve → ...or think of it as the facial nerve is the deepest major structure):
Actually, the classic teaching is from lateral to medial (superficial to deep):
- Facial nerve (CN VII) — the most surgically important structure. It enters the gland after exiting the stylomastoid foramen and divides into its 5 terminal branches within the gland:
- Temporal
- Zygomatic
- Buccal
- Marginal mandibular
- Cervical
- Mnemonic: "To Zanzibar By Motor Car" or "Two Zebras Bit My Cat"
- Retromandibular vein (formed by superficial temporal + maxillary veins)
- External carotid artery (deepest of the three)
Why does the facial nerve matter so much? The facial nerve runs through the parotid gland parenchyma. Any parotid pathology — infection, abscess, tumour, surgery — can damage the facial nerve, causing facial nerve palsy. This is why facial nerve palsy is a complication of parotitis [2].
Stensen's Duct [2]:
- Arises from the anterior border of the parotid gland
- 4–7 cm long
- Runs superficially over the masseter muscle, then pierces the buccinator muscle
- Opens opposite the upper second molar on the buccal mucosa (the parotid papilla)
- This is where you look when examining for purulent discharge in suspected parotitis
- The parotid gland produces purely serous (watery) saliva — rich in amylase (hence elevated serum amylase in parotitis), water, and electrolytes
- Contributes approximately 25% of total salivary volume at rest, but ~50% during stimulated secretion (eating)
- Saliva has antimicrobial properties: contains IgA, lysozyme, lactoferrin, and histatins
- Salivary flow is stimulated by parasympathetic innervation via the glossopharyngeal nerve (CN IX) → inferior salivatory nucleus → otic ganglion → auriculotemporal nerve → parotid
- Sympathetic innervation (from superior cervical ganglion) produces a small volume of thick, protein-rich secretion
Why does serum amylase rise in parotitis? The parotid gland is the major source of salivary amylase. When the gland is inflamed, amylase leaks into the blood. Elevated serum amylase in the absence of pancreatitis supports the diagnosis of parotitis [2].
- Arterial supply: Branches of the external carotid artery (including the transverse facial artery)
- Venous drainage: Retromandibular vein
- Lymphatic drainage: Intraparotid lymph nodes (superficial and deep) → deep cervical chain
- The parotid gland is unique among salivary glands in that it contains intraglandular lymph nodes (because the lymph nodes were encapsulated during embryological development before the gland fully formed). This means metastatic lymph node disease (e.g., from scalp SCC, melanoma) can present as an intraparotid mass
- The parotid gland is enclosed within a fibrous capsule derived from the investing layer of deep cervical fascia
- The deep lobe of the parotid is closely related to the parapharyngeal space — this is why deep lobe parotid infections can extend to form parapharyngeal abscesses [2]
Etiology
Acute suppurative parotitis is most commonly caused by Staphylococcus aureus [1][2].
It is often polymicrobial, reflecting retrograde contamination from the oral flora [2].
| Category | Organisms |
|---|---|
| Aerobes | Staphylococcus aureus (most common) [1][2], Streptococcus viridans, Streptococcus pneumoniae, Streptococcus pyogenes, Haemophilus influenzae, Mycobacterium spp., Enterobacteriaceae, Pseudomonas aeruginosa, Eikenella corrodens [2] |
| Anaerobes | Peptostreptococcus, Actinomyces, Bacteroides, Fusobacterium, Prevotella, Porphyromonas [2] |
Key points:
- In immunocompetent patients: S. aureus and oral streptococci predominate
- In immunocompromised patients: Gram-negative organisms (Pseudomonas, Enterobacteriaceae) and MRSA become more important — requiring broader-spectrum empirical cover
- Mycobacterial parotitis (both TB and non-tuberculous mycobacteria/NTM) should be considered in Hong Kong given the intermediate TB prevalence. NTM parotitis is classically seen in children (presenting as a chronic, non-tender parotid mass with violaceous skin)
- Actinomycosis is a rare but important cause — presents as a chronic, indolent infection with draining sinuses and "sulfur granules"
| Virus | Notes |
|---|---|
| Mumps (Paramyxovirus) | Commonest cause of viral parotitis [3]. Bilateral parotid swelling in 70% of cases. Preceded by prodrome (fever, malaise, myalgia). Orchitis in post-pubertal males (15–30%). Complications: meningitis, encephalitis, pancreatitis, deafness |
| Coxsackievirus | Can cause parotitis as part of hand-foot-mouth disease spectrum [3] |
| CMV (Cytomegalovirus) | Especially in immunocompromised (HIV, transplant patients) [3] |
| Influenza | Rare cause [3] |
| Parainfluenza | [2] |
| Herpes simplex virus (HSV) | [2] |
| Epstein-Barr virus (EBV) | Parotitis as part of infectious mononucleosis; also associated with lymphoepithelial carcinoma in endemic areas [2] |
| HIV | Causes benign lymphoepithelial cysts (bilateral, painless parotid enlargement); also DILS (diffuse infiltrative lymphocytosis syndrome) [2] |
Viral vs. Bacterial Parotitis — Key Distinctions
Causes of bilateral parotid enlargement [4]:
| Cause | Mechanism |
|---|---|
| Pseudoparotomegaly (e.g., masseter hypertrophy) | Not true parotid enlargement — masseter muscle bulk mimics parotid swelling. Seen in bruxism or habitual clenching [4] |
| Bulimia nervosa | Repeated vomiting → chronic stimulation of salivary glands → sialadenosis (non-inflammatory hypertrophy of acinar cells). The acid exposure also triggers compensatory hypersecretion [4] |
| Alcoholic cirrhosis | Fatty infiltration of parotid glands + autonomic neuropathy → sialadenosis [4] |
| Diabetes mellitus | Fatty infiltration of parotid glands → painless bilateral enlargement [4] |
| Hypothyroidism | Mucopolysaccharide deposition in glandular tissue [4] |
| Drugs (e.g., phenytoin) | Drug-induced sialadenosis [4] |
| Sjögren's syndrome | Autoimmune lymphocytic infiltration → chronic inflammation → progressive glandular enlargement. Can be bilateral. Associated with dry eyes (keratoconjunctivitis sicca) and dry mouth (xerostomia) |
| Sarcoidosis | Non-caseating granulomatous infiltration. Heerfordt syndrome = uveoparotid fever (bilateral parotid enlargement + anterior uveitis + facial nerve palsy + fever) |
| IgG4-related disease | Storiform fibrosis and IgG4+ plasma cell infiltration → bilateral painless parotid/submandibular enlargement (previously called Mikulicz disease) |
Bilateral Parotid Enlargement — Think Non-Infectious!
When you see bilateral painless parotid enlargement without signs of infection (no fever, no tenderness, no pus), think: bulimia, alcohol, diabetes, hypothyroidism, Sjögren's, sarcoidosis, HIV, or drugs. This is a classic exam question [4].
Pathophysiology
The pathogenesis follows a logical sequence [2]:
Step-by-step explanation:
-
Salivary stasis — any condition that reduces salivary flow (dehydration, anticholinergics, duct obstruction) removes the gland's primary defence mechanism: the continuous forward flushing of saliva out through the duct. Saliva also contains antimicrobial factors (IgA, lysozyme) — reduced production means reduced local immunity
-
Retrograde seeding of Stensen's duct by mixed oral flora — normally, the unidirectional flow of saliva prevents bacteria from ascending the duct. When flow stops, bacteria from the oral cavity (which harbours >700 species) can travel retrogradely up the duct into the gland [2]
-
Acute bacterial infection — the bacteria multiply within the gland's ductal system and parenchyma, triggering an acute inflammatory response (neutrophilic infiltration, oedema, pus formation)
-
May be complicated by abscess formation — contiguous infection can lead to discrete abscess collections within the gland, or infection can spread via haematogenous seeding to intraparotid or periparotid lymph nodes [2]
-
Extension to adjacent spaces — the deep lobe of the parotid is intimately related to the parapharyngeal space. Infection can track into this space, causing parapharyngeal abscess, which in turn can lead to Lemierre's syndrome (septic jugular thrombophlebitis) [2]
- The mumps virus (a Paramyxovirus, genus Rubulavirus) is transmitted via respiratory droplets
- The virus infects the upper respiratory tract epithelium → primary viraemia → disseminates to salivary glands (tropism for ductal epithelium) → replicates in parotid ductal and acinar cells
- Triggers a lymphocytic inflammatory infiltrate → interstitial oedema → gland swelling
- The swelling is diffuse and non-suppurative (no pus) — this is because it's a viral process with lymphocytic (not neutrophilic) infiltration
- Incubation period: 14–25 days (average 16–18 days)
- Virus can also disseminate to other glandular/neural tissues: testes (orchitis), pancreas (pancreatitis), meninges (meningitis), cochlea (sensorineural deafness)
- This is the mechanism behind bilateral parotid enlargement in bulimia, alcoholism, DM, hypothyroidism
- It represents non-inflammatory, non-neoplastic acinar hypertrophy — the acinar cells (particularly serous cells) enlarge due to metabolic/autonomic dysfunction
- In bulimia: chronic vomiting stimulates gustatory-salivary reflexes repeatedly; the acid exposure to the oral cavity may also drive compensatory salivary hyperactivity → work hypertrophy of acinar cells
- In alcoholism/cirrhosis: autonomic neuropathy (affecting parasympathetic innervation of the parotid) leads to degranulation and hypertrophy of acinar cells; additionally, fatty infiltration contributes
- Key point: sialadenosis is painless and non-tender (no inflammation)
Classification
| Category | Subtypes |
|---|---|
| Infectious | Bacterial (suppurative), Viral (non-suppurative), Mycobacterial, Fungal (rare) |
| Obstructive | Sialolithiasis, Ductal stricture, Mucous plug |
| Autoimmune | Sjögren's syndrome, IgG4-related disease |
| Granulomatous | Sarcoidosis, TB |
| Metabolic/Systemic | Bulimia, Alcoholic cirrhosis, DM, Hypothyroidism |
| Drug-induced | Phenytoin, anticholinergics (indirect — via reduced flow), iodine-containing contrast |
| Neoplastic | Primary or metastatic parotid tumours (not parotitis per se, but can present with parotid enlargement ± secondary infection) |
| Radiation-induced | Post-radiotherapy sialadenitis |
| Type | Features |
|---|---|
| Acute parotitis | Sudden onset, < 4 weeks. Usually infectious (bacterial or viral) |
| Chronic parotitis | Recurrent episodes or persistent inflammation > 3 months. Think: recurrent juvenile parotitis (in children), Sjögren's, IgG4-RD, chronic sialadenitis from stones |
| Recurrent parotitis of childhood | Recurrent episodes of acute parotitis in children (age 3–6), often unilateral, aetiology unclear (possibly related to ductal ectasia and reduced salivary flow). Usually self-limiting by puberty |
| Pattern | Think of... |
|---|---|
| Unilateral | Bacterial suppurative parotitis, sialolithiasis, parotid tumour, parotid abscess |
| Bilateral | Viral parotitis (mumps), Sjögren's, bulimia, alcoholism, DM, hypothyroidism, HIV, sarcoidosis, drugs [4] |
Clinical Features
| Symptom | Pathophysiological Basis |
|---|---|
| Sudden onset of firm swelling in the preauricular/postauricular region extending to the angle of mandible [2] | Acute inflammatory oedema and cellular infiltration of the parotid gland parenchyma within its fascial capsule. The gland is bounded by the structures described above (EAC, mandible angle, zygomatic arch), so swelling tracks along these landmarks |
| Exquisite local pain and tenderness [2] | Rapid swelling within a tight fascial capsule → increased intraglandular pressure → stimulation of pain fibres. Additionally, inflammatory mediators (prostaglandins, bradykinin) directly sensitize nociceptors |
| Erythema and warmth of overlying skin | Classical signs of acute inflammation (rubor, calor) — vasodilation and increased blood flow from inflammatory mediators (histamine, NO) |
| Trismus (difficulty opening mouth) [2] | The parotid gland is intimately related to the masseter muscle and the temporomandibular joint. Inflammation and oedema in the parotid region irritate and splint the muscles of mastication → reflex muscle spasm → limited jaw opening |
| Dysphagia (difficulty swallowing) [2] | Deep lobe swelling can impinge on the parapharyngeal space and oropharynx, narrowing the pharyngeal lumen. Pain also inhibits swallowing |
| Fever and chills [2] | Systemic inflammatory response to bacterial infection (IL-1, IL-6, TNF-α → hypothalamic PGE2 → raised thermostat set point). Chills/rigors indicate bacteraemia |
| Generalized toxicity (malaise, anorexia) [2] | Cytokine-mediated systemic effects of infection/sepsis |
| Foul taste in mouth | Purulent material draining from Stensen's duct into the oral cavity |
| Xerostomia (dry mouth) | If salivary flow is obstructed or the gland is severely damaged, reduced salivary output to the mouth |
| Sign | Pathophysiological Basis |
|---|---|
| Firm, erythematous swelling involving the preauricular and postauricular region extending to the angle of mandible [2] | Parotid gland boundaries: anterior to EAC, overlying masseter, extending to mandibular angle. The gland is encapsulated, so the swelling tends to be diffuse within these boundaries |
| Purulent material expressed from the orifice of Stensen's duct (opposite upper 2nd molar) on bimanual massage of the gland [1][2] | This is the hallmark sign of suppurative parotitis. Bacteria within the gland produce pus; external pressure on the gland forces this pus anterogradely through Stensen's duct. This sign distinguishes suppurative from viral parotitis (viral parotitis does NOT produce purulent discharge) [2] |
| Induration of the gland | Inflammatory infiltrate and oedema within the parenchyma |
| Elevation of ear lobe | The parotid gland lies just below and anterior to the ear. Significant swelling lifts the ear lobe upward and outward — a classic clinical sign |
| Fluctuance (late sign) | Indicates abscess formation — liquefactive necrosis has produced a discrete pus collection within the gland |
| Facial nerve palsy (rare but important) | The facial nerve runs through the parotid gland. Severe infection, abscess formation, or surgical intervention can damage the nerve → lower motor neuron facial weakness. If facial nerve palsy is present with a parotid mass, always consider malignancy (parotid tumour with perineural invasion) |
| Trismus (on examination) | Measured as inter-incisor distance < 35mm. Reflects irritation of masticatory muscles |
| Cervical lymphadenopathy | Regional lymph nodes (upper deep cervical chain) become reactive in response to infection |
Specific Features by Aetiology
- Distinguished from suppurative parotitis by a prodromal period (2–3 days of fever, headache, malaise, myalgia, anorexia) followed by acute swelling of the gland
- Lasts 5–10 days and is often bilateral (70%) [2]
- Does NOT give purulent discharge from Stensen's duct [2]
- Diagnosis by clinical presentation and serology (mumps IgM, or 4-fold rise in IgG) [3]
- The swelling characteristically obscures the angle of the mandible
- Pain is worsened by eating (salivary stimulation) or acidic foods (lemon juice — sometimes used as a provocative test)
- Bilateral, painless, progressive parotid enlargement
- Due to benign lymphoepithelial cysts or DILS
- No signs of acute infection
- CD4 count typically 200–500 cells/μL
- May be the presenting feature of HIV
The Stensen's Duct Exam
A common mistake is forgetting to examine the intraoral orifice of Stensen's duct (opposite the upper 2nd molar). In suspected parotitis, you must massage the gland externally and look for purulent discharge at the duct opening. This is the single most important clinical sign to differentiate suppurative from non-suppurative parotitis. If you see pus, send it for Gram stain and culture.
Ear Lobe Elevation
In significant parotid swelling (whether from infection, tumour, or other causes), the ear lobe is displaced upward and outward. This is a subtle but important sign on inspection — it immediately tells you the swelling is arising from the parotid rather than from the submandibular gland or cervical lymph nodes.
| Anatomical Relationship | Clinical Consequence |
|---|---|
| Parotid gland encased in tight fascial capsule | Pain (pressure within capsule), firm swelling |
| Stensen's duct opens opposite upper 2nd molar | Purulent discharge visible intraorally; can be expressed by massage |
| Facial nerve (CN VII) traverses the gland | Facial nerve palsy in severe infection/abscess/surgery |
| Deep lobe abuts parapharyngeal space | Parapharyngeal abscess; airway compromise; dysphagia |
| Gland overlies masseter and near TMJ | Trismus |
| Gland lies inferior/anterior to ear | Ear lobe elevation |
| Intraglandular lymph nodes present | Infection can seed lymph nodes → abscess; also relevant for metastatic disease |
High Yield Summary
- Acute suppurative parotitis = dehydrated/debilitated/post-op patient + unilateral tender parotid swelling + pus from Stensen's duct + S. aureus most common organism
- Viral parotitis = mumps (commonest viral cause) + bilateral + prodrome + no pus from duct + self-limiting 5–10 days + diagnose clinically + serology
- Pathophysiology = reduced salivary flow → stasis → retrograde bacterial seeding up Stensen's duct → suppurative infection → ± abscess
- Risk factors = dehydration, post-op, elderly, anticholinergics, duct obstruction, poor oral hygiene, immunosuppression
- Bilateral painless parotid enlargement differential: bulimia, alcoholic cirrhosis, DM, hypothyroidism, drugs (phenytoin), Sjögren's, HIV, sarcoidosis, pseudoparotomegaly (masseter hypertrophy)
- Key clinical sign = express pus from Stensen's duct orifice (opposite upper 2nd molar) by massaging the gland
- Serum amylase elevated in parotitis (parotid is the main source of salivary amylase)
- Facial nerve runs through the gland → facial nerve palsy is a complication of parotitis/abscess/surgery
- Stensen's duct = 4–7 cm long, opens opposite upper 2nd molar
- Complications: airway obstruction, facial nerve palsy, septicaemia, parapharyngeal abscess (→ Lemierre's syndrome), osteomyelitis of adjacent bone
Active Recall - Parotitis
[1] Lecture slides: GC 217. Facial nerve palsy and salivary gland diseases.pdf, p50 [2] Senior notes: felixlai.md, sections 321–323 (Parotitis) [3] Lecture slides: GC 217. Facial nerve palsy and salivary gland diseases.pdf, p51 [4] Lecture slides: GC 217. Facial nerve palsy and salivary gland diseases.pdf, p58
Differential Diagnosis of Parotitis
When a patient presents with a swelling in the parotid region, the first clinical question — before you even think about which type of parotitis — is: "Is it really a parotid swelling?" [5]. Many structures in and around the parotid region can mimic parotid pathology. Then, once you've confirmed it's genuinely parotid, you need to differentiate between infectious, inflammatory, obstructive, autoimmune, and neoplastic causes.
The approach to differential diagnosis is best understood by working through the anatomy systematically and then considering the clinical context (acute vs. chronic, unilateral vs. bilateral, painful vs. painless, with or without pus).
This is the first question on physical examination [5]. Several conditions can masquerade as a parotid mass:
| Mimic | Why It Can Be Confused | How to Distinguish |
|---|---|---|
| Masseter hypertrophy | The masseter muscle lies deep to the parotid gland. Hypertrophy (from bruxism or habitual clenching) causes bilateral swelling over the angle of the mandible that mimics parotid enlargement [4][5] | Ask about bruxism/clenching. The swelling is hard and most prominent when the patient clenches their teeth. It moves with jaw clenching. No pus from Stensen's duct. CT shows enlarged masseter without parotid abnormality |
| Enlarged cervical lymph nodes | Upper deep cervical or periparotid lymph nodes can present as a swelling near the angle of the mandible [5] | Typically more discrete, mobile, and located more in the neck (Level I–II). Multiple nodes may be palpable. Look for a source of infection or malignancy in the drainage territory (scalp, ear, face, oral cavity) |
| Lipoma | Superficial lipomas in the parotid region can mimic a parotid mass [5] | Soft, non-tender, mobile, well-defined. No pus from duct. Imaging shows characteristic fat signal |
| Vascular malformations | Haemangiomas or venous malformations in the parotid region [5] | May be compressible, bluish discolouration, may enlarge with Valsalva. MRI is diagnostic |
| Oral cavity mass with direct extension to submandibular space | A floor-of-mouth or sublingual mass can extend posteriorly and mimic submandibular or even parotid pathology [5] | Intraoral examination is mandatory [5] — will reveal the primary mucosal lesion |
| First branchial cleft cyst | Type I and II first branchial cleft cysts pass through or near the parotid gland in close proximity to the facial nerve [6] | Typically presents in childhood/young adulthood as recurrent parotid swelling ± infection. May have a sinus tract near the ear. Imaging shows a cystic lesion within or adjacent to the parotid |
| Pre-auricular lymphadenopathy | Superficial pre-auricular nodes drain the temporal scalp, eyelids, and conjunctiva | More superficial, discrete, mobile. Look for conjunctivitis, periorbital infection, or scalp pathology |
The Palpation Principle
On palpation, confirm the lesion is not arising from the skin [7]. Also, it is difficult to ascertain a mass is truly a parotid tumour clinically [7] — you often need imaging (ultrasound ± CT/MRI) to confirm the lesion's origin. Palpate the ducts for stones and express pus [7] — this simple manoeuvre is the most important bedside test for parotitis.
Differentiate between infection and neoplasm [8]:
- Pain — After a meal? Acute onset? [8] — Meal-related pain suggests obstructive pathology (sialolithiasis causing post-prandial swelling). Acute onset pain suggests infection. Chronic dull pain or painless mass suggests neoplasm or autoimmune
- Swelling — Persistent or intermittent? [8] — Intermittent swelling (waxing and waning, worse with meals) is classic for sialolithiasis. Persistent and progressive swelling suggests neoplasm. Recurrent episodes suggest chronic sialadenitis or recurrent parotitis of childhood
- Presence of symptoms of acute infection — fever, tenderness, pus [8] — If present → infectious parotitis
Step 3: Systematic Differential Diagnosis
The differential diagnosis of parotid swelling can be organized by mechanism:
| Differential | Key Features | Distinguishing Points |
|---|---|---|
| Acute suppurative parotitis | Dehydrated, infirm, elderly [1]. Sudden onset tender swelling. Pus from duct opening. S. aureus most common [1] | Unilateral, high fever, purulent discharge from Stensen's duct. Often post-operative. Polymicrobial [2] |
| Viral parotitis (mumps = commonest) | Commonest viral cause — mumps [3]. Also Coxsackie virus, CMV, Influenza [3] | Bilateral (70%), prodromal period, NO pus from duct, self-limiting 5–10 days. Diagnosis by clinical and serology [3] |
| Acute bacterial sialadenitis (non-calculous) | Identical presentation to suppurative parotitis but without demonstrable stone [9]. Typically affects older adults, malnourished or post-operative patients. Commonly caused by S. aureus but also S. viridans, S. pneumoniae, H. influenzae, and Bacteroides [9] | Sudden onset of very firm and tender swelling of the gland. Fever and chills with fairly marked systemic toxicity. Purulent discharge from the affected duct orifice [9] |
| Differential | Key Features | Distinguishing Points |
|---|---|---|
| Sialolithiasis | Recurrent, meal-related swelling and pain of the parotid (or more commonly submandibular) gland. Waxing and waning symptoms [9] | Pain is aggravated by eating or anticipation of eating (salivary stimulation increases flow against obstruction → ductal distension → pain). Stone may be palpable along the duct. Imaging (X-ray, US, CT) shows calcified stone. If secondary infection develops → becomes suppurative sialadenitis |
| Ductal stricture / mucous plug | Similar meal-related obstructive symptoms but no calculus on imaging | Usually post-inflammatory. Sialography or sialendoscopy may demonstrate stricture |
Why does eating worsen obstructive parotid pain? When you eat (or even think about food), parasympathetic stimulation via CN IX drives salivary secretion. If the duct is blocked by a stone, the increased secretory pressure has nowhere to go → the gland and duct distend → pain. This "mealtime syndrome" is pathognomonic for obstructive salivary disease.
| Differential | Key Features | Distinguishing Points |
|---|---|---|
| Chronic sialadenitis | Mild pain, worsens after meal. Recurrent parotid or submandibular swelling after meal [10]. Low-grade chronic infection → progressive glandular destruction [9] | History of recurrent episodes. Gland may feel firm and fibrotic. Reduced salivary flow. Can be caused by autoimmune disease (Sjögren syndrome) [10] |
| Sjögren's syndrome | Chronic inflammatory disorder with diminished lacrimal and salivary secretions → dry eyes and mouth (sicca complex) [9]. Gradual bilateral swelling of parotid or submandibular glands [9] | Bilateral and painless. Associated xerostomia and keratoconjunctivitis sicca. Positive anti-Ro (SSA) / anti-La (SSB) antibodies. Schirmer test positive. Lip biopsy shows focal lymphocytic sialadenitis (focus score ≥ 1). Autoimmune sialadenitis causes parenchymal destruction and dilation of intraglandular ducts [9] |
| Sarcoidosis | Bilateral painless parotid enlargement due to granulomatous infiltration [9] | Non-caseating granulomas on biopsy. Elevated serum ACE. May have pulmonary sarcoidosis. Heerfordt syndrome = uveoparotid fever (parotid enlargement + anterior uveitis + facial nerve palsy + fever). CXR may show bilateral hilar lymphadenopathy |
| IgG4-related disease | Bilateral painless parotid/submandibular enlargement | Elevated serum IgG4. Storiform fibrosis and IgG4+ plasma cells on biopsy. May have associated autoimmune pancreatitis, retroperitoneal fibrosis. Previously called Mikulicz disease or Kuttner's tumour (when affecting submandibular gland) |
| Differential | Key Features | Distinguishing Points |
|---|---|---|
| Benign salivary gland tumour (pleomorphic adenoma, Warthin tumour) | Slow-growing, painless, unilateral parotid mass. Mobile, firm, well-defined [9] | No facial nerve involvement. Pleomorphic adenoma is the most common parotid tumour overall. Warthin tumour is the second most common and is strongly associated with smoking; may be bilateral |
| Malignant salivary gland tumour (mucoepidermoid carcinoma, adenoid cystic carcinoma, etc.) | Progressive, may be painful. Facial weakness is high suspicion of malignant involvement of parotid gland [11]. May have skin fixation, cervical lymphadenopathy | Parotid tumour must be distinguished from Bell's palsy [11]. Perineural invasion (especially adenoid cystic carcinoma) causes pain and CN VII palsy. FNA or core biopsy needed for tissue diagnosis |
| Metastasis from other tumours | History of previous skin cancer (SCC, melanoma) of the scalp/face [11] | Parotid gland contains intraglandular lymph nodes — metastatic deposits from cutaneous malignancy of the scalp, ear, or face can present as a parotid mass |
| Lymphoma | May present as a parotid mass (intraglandular lymph nodes) | Consider in patients with Sjögren's syndrome (40-fold increased risk of non-Hodgkin lymphoma). Also tonsils and tongue base may be presenting site for lymphoma [12] |
Facial Nerve Palsy + Parotid Mass = Malignancy Until Proven Otherwise
Facial weakness in the context of a parotid mass is a red flag for malignancy [11]. Benign tumours (even large ones) virtually never cause facial nerve palsy because they displace rather than invade the nerve. Malignant tumours invade perineurally. This distinction is critical — parotid tumour must be distinguished from Bell's palsy [5][11].
Causes of bilateral parotid enlargement [4]:
| Cause | Mechanism | Key Distinguishing Feature |
|---|---|---|
| Pseudoparotomegaly, e.g. masseter hypertrophy | Not true parotid — masseter muscle bulk | Hardens on clenching |
| Bulimia nervosa | Repeated vomiting → chronic gustatory stimulation → sialadenosis (acinar hypertrophy) | Young female, dental erosion, Russell's sign (knuckle calluses), metabolic alkalosis |
| Alcoholic cirrhosis | Fatty infiltration + autonomic neuropathy → sialadenosis | Stigmata of chronic liver disease (spider naevi, palmar erythema, jaundice) |
| DM | Fatty infiltration of glands | Known diabetic or features of undiagnosed DM |
| Hypothyroidism | Mucopolysaccharide deposition | Myxoedema features, raised TSH |
| Drugs, e.g. phenytoin | Drug-induced sialadenosis | Drug history |
| Sjögren's syndrome | Autoimmune lymphocytic infiltration | Sicca symptoms + serology |
| HIV | Benign lymphoepithelial cysts / DILS | Risk factors, HIV test, bilateral cystic lesions on imaging |
| Sarcoidosis | Granulomatous infiltration | Bilateral hilar lymphadenopathy, elevated ACE, non-caseating granulomas |
| Differential | Key Features |
|---|---|
| Salivary cysts (mucocele, ranula, lymphoepithelial cyst) | Cystic lesion on imaging. Lymphoepithelial cysts are characteristic of HIV [11] |
| Chronic sclerosing sialadenitis (Kuttner's tumour) | Hard, tumour-like enlargement of submandibular gland (rarely parotid). Now recognized as part of IgG4-related disease spectrum [11] |
| Regional lymphadenopathy | Reactive or malignant cervical lymph nodes adjacent to the parotid [11] |
| Recurrent parotitis of childhood | Recurrent episodes of acute unilateral parotitis in children (age 3–6). Aetiology unclear — likely related to ductal ectasia, sialectasis, and reduced local immunity. Self-limiting by puberty |
| Radiation sialadenitis | Post-radiotherapy to H&N region. Acute phase: painful swelling within days. Chronic phase: progressive xerostomia due to acinar atrophy |
| Feature | Suppurative Parotitis | Viral Parotitis | Sialolithiasis | Neoplasm | Autoimmune / Systemic |
|---|---|---|---|---|---|
| Onset | Acute (hours–days) | Acute with prodrome | Episodic | Gradual (weeks–months) | Gradual |
| Laterality | Usually unilateral | Often bilateral | Unilateral | Usually unilateral | Usually bilateral |
| Pain | Severe, constant | Moderate, diffuse | Meal-related (colicky) | Painless (unless malignant) | Mild or painless |
| Pus from duct | Yes | No | ± (if secondary infection) | No | No |
| Fever | High | Low-grade | ± | No (unless superinfected) | No |
| Facial nerve palsy | Rare (abscess) | No | No | Yes = malignancy | Rare (sarcoidosis) |
| Key investigation | Gram stain/culture of pus | Serology | Imaging (US, CT) | FNA/core biopsy + imaging | Serology (SSA/SSB, IgG4), lip biopsy |
High Yield Summary
- First question: Is it really a parotid swelling? — rule out masseter hypertrophy, cervical LNs, lipoma, vascular malformation, branchial cleft cyst
- History discriminators: Acute onset + fever + pus → infection. Meal-related intermittent swelling → sialolithiasis. Persistent progressive painless mass → neoplasm. Bilateral painless → systemic/autoimmune/metabolic
- Palpate the ducts for stones and express pus — the most important bedside manoeuvre
- Bilateral parotid enlargement DDx: pseudoparotomegaly (masseter hypertrophy), bulimia, alcoholic cirrhosis, DM, hypothyroidism, drugs (phenytoin), Sjögren's, sarcoidosis, HIV
- Facial nerve palsy + parotid mass = malignancy until proven otherwise — benign tumours do not cause CN VII palsy
- Neoplasm DDx: primary benign (pleomorphic adenoma, Warthin), primary malignant (mucoepidermoid, adenoid cystic), metastatic (from scalp/face SCC or melanoma), lymphoma
- Chronic sialadenitis: mild pain, worsens after meal, recurrent swelling — can be caused by Sjögren's or sialolithiasis
Active Recall - Differential Diagnosis of Parotitis
References
[1] Lecture slides: GC 217. Facial nerve palsy and salivary gland diseases.pdf, p50 [2] Senior notes: felixlai.md, sections 321–323 [3] Lecture slides: GC 217. Facial nerve palsy and salivary gland diseases.pdf, p51 [4] Lecture slides: GC 217. Facial nerve palsy and salivary gland diseases.pdf, p58 [5] Lecture slides: GC 217. Facial nerve palsy and salivary gland diseases.pdf, p38 [6] Senior notes: felixlai.md, section 295 [7] Lecture slides: GC 217. Facial nerve palsy and salivary gland diseases.pdf, p41 [8] Lecture slides: GC 217. Facial nerve palsy and salivary gland diseases.pdf, p37 [9] Senior notes: felixlai.md, section 327 [10] Lecture slides: GC 217. Facial nerve palsy and salivary gland diseases.pdf, p53 [11] Senior notes: felixlai.md, section 336 [12] Senior notes: felixlai.md, section 369
Diagnostic Criteria, Algorithm, and Investigations for Parotitis
Diagnostic Criteria
Parotitis — unlike conditions such as rheumatic fever or SLE — does not have formal "diagnostic criteria" with a points-based scoring system. Instead, the diagnosis is made through a combination of clinical features, physical examination findings, and targeted investigations. The approach is fundamentally clinical, with investigations used to:
- Confirm the diagnosis (is it really parotitis?)
- Identify the aetiology (bacterial vs. viral vs. autoimmune vs. obstructive vs. neoplastic)
- Guide management (identify the organism, detect complications like abscess)
That said, here are the key diagnostic pillars for each major type:
| Pillar | Detail |
|---|---|
| Clinical context | Dehydrated, infirm, elderly or post-operative patient [1] |
| Clinical features | Acute onset of unilateral tender swelling in the parotid region + fever + systemic toxicity [2] |
| Pathognomonic sign | Pus from duct opening — purulent material expressed from the orifice of Stensen's duct (opposite upper 2nd molar) on bimanual massage of the gland [1][2] |
| Microbiological confirmation | Gram stain and culture of expressed pus or FNA aspirate — S. aureus is the most common organism [1][2] |
| Supportive biochemistry | Elevated serum amylase in the absence of pancreatitis supports parotid gland involvement [2] |
The diagnosis of acute suppurative parotitis is essentially clinical — a sick patient with a tender parotid swelling and pus expressible from Stensen's duct. You don't need imaging to make the diagnosis, but you do need cultures to guide antibiotic therapy and imaging if you suspect abscess or stone.
| Pillar | Detail |
|---|---|
| Clinical features | Prodromal period (fever, malaise, headache, myalgia) → bilateral parotid swelling lasting 5–10 days. No purulent discharge from Stensen's duct [2][3] |
| Confirmation | Diagnosis by clinical and serology [3] — mumps-specific IgM (acute infection) or 4-fold rise in paired IgG titres. Mumps virus PCR from saliva/urine/CSF in selected cases |
| Epidemiological context | Unvaccinated individual, or recent outbreak exposure. In Hong Kong, check MMR vaccination history |
The following algorithm walks through the clinical reasoning process from presentation to aetiological diagnosis:
The Algorithm in Plain English
- First: Confirm it's truly parotid (history + examination ± ultrasound)
- Second: Is it acute or chronic?
- If acute: Look for pus from Stensen's duct → if yes, it's suppurative parotitis → send cultures, start antibiotics → if no response at 48 hours, CT to rule out abscess
- If acute but no pus and bilateral with prodrome: Think viral → serology
- If chronic/recurrent and unilateral: Think stone or chronic sialadenitis → imaging
- If chronic/recurrent and bilateral: Think systemic/autoimmune → targeted serology and investigations
Investigation Modalities
1. Bedside / Clinical Examination
Intraoral inspection is the first and most important "investigation" [14]:
| What to Look For | Significance |
|---|---|
| Parotid duct opening (opposite upper 2nd molar) | Inspect for erythema, oedema of the papilla, purulent discharge [14] |
| Submandibular duct opening (sublingual caruncle, floor of mouth near frenulum) | If submandibular gland disease is suspected [14] |
| Floor of mouth swelling | May indicate submandibular stone, ranula, or floor of mouth tumour [14] |
| Tumour in floor of mouth/oral cavity | Oral cavity malignancy can obstruct ducts or mimic salivary pathology [14] |
| Pus in the salivary duct openings | Pathognomonic for suppurative sialadenitis — if pus is expressible, collect it for Gram stain and culture [1][14] |
Palpation [7]:
- Confirm the lesion is not arising from the skin (lipoma, sebaceous cyst) [7]
- Palpate the ducts for stones — run your finger along the course of Stensen's duct (over the masseter) or Wharton's duct (floor of mouth) to feel for a palpable calculus [7]
- Express pus — apply external pressure over the gland and watch the duct opening intraorally for purulent discharge [7]
- Note that it is difficult to ascertain a mass is a parotid tumour on palpation alone — imaging is usually needed [7]
- Assess all 5 branches of CN VII (temporal, zygomatic, buccal, marginal mandibular, cervical)
- Raise eyebrows (temporal), close eyes tightly (zygomatic), puff cheeks/smile (buccal), show lower teeth/depress lower lip (marginal mandibular), tense platysma (cervical)
- Why? Facial nerve palsy in the context of parotid pathology is a red flag for malignancy or severe abscess [11]. Document specific branch involvement if present
| Investigation | Expected Finding in Parotitis | Interpretation / Rationale |
|---|---|---|
| Full blood count (CBC) | Leukocytosis with neutrophilia (bacterial); lymphocytosis or normal WBC (viral) | Neutrophilia = bacterial infection driving neutrophil release from bone marrow. Lymphocytosis is characteristic of viral infections (mumps, EBV, CMV) |
| CRP / ESR | Elevated | Non-specific markers of inflammation. CRP rises within 6–12 hours of infection onset (synthesized by hepatocytes in response to IL-6). Useful for monitoring treatment response |
| Serum amylase | Elevated | Elevated serum amylase in the absence of pancreatitis supports the clinical suspicion of parotid gland involvement [2]. The parotid gland is the main source of salivary amylase (isoamylase S-type). If needed, amylase isoenzyme fractionation can confirm salivary (not pancreatic) origin |
| Blood cultures | May be positive in bacteraemic patients | Essential in systemically unwell patients (fever, rigors, sepsis). Identifies haematogenous spread and guides targeted antibiotic therapy |
| Serology | Mumps IgM positive (acute infection); 4-fold rise in paired IgG; EBV VCA-IgM (if EBV suspected); CMV IgM | Diagnosis by clinical and serology for viral parotitis [3]. IgM appears early (within days of symptom onset) and indicates acute infection. IgG rises later and persists (indicates past exposure or convalescence) |
| Viral PCR | Mumps RNA in saliva, throat swab, or urine | More sensitive and rapid than serology in the acute phase. Useful for public health notification and outbreak investigation |
| Renal function, electrolytes | May show dehydration (elevated urea, creatinine, Na+) | Dehydration is both a cause and a consequence of parotitis. Guides IV fluid resuscitation |
| HbA1c / fasting glucose | May reveal undiagnosed DM | DM predisposes to parotitis (sialadenosis + immunosuppression) and bilateral parotid enlargement |
| TFTs | Hypothyroidism | Hypothyroidism causes bilateral parotid enlargement (mucopolysaccharide deposition) |
| Autoimmune serology (if chronic/bilateral) | Anti-Ro/SSA, Anti-La/SSB, ANA, RF, IgG4, serum ACE | Anti-Ro/SSB positive in Sjögren's. Elevated IgG4 in IgG4-related disease. Elevated ACE in sarcoidosis |
| HIV test | Positive | Consider in bilateral parotid enlargement, especially with lymphoepithelial cysts on imaging |
Why check amylase isoenzymes? Total serum amylase is elevated in both pancreatitis and parotitis. The S-type (salivary) isoamylase comes from the parotid gland, while the P-type (pancreatic) isoamylase comes from the pancreas. In parotitis, S-type is elevated with normal P-type. In pancreatitis, it's the reverse. Lipase is elevated only in pancreatitis (not in parotitis), so a normal lipase with elevated amylase strongly favours parotitis over pancreatitis.
| Investigation | Method and Key Points | Interpretation |
|---|---|---|
| Gram stain and culture of expressed pus | Purulent drainage from Stensen's duct should be collected for Gram stain and culture [2]. Collect at the duct orifice using a sterile swab or aspirate as pus is being expressed | Gram-positive cocci in clusters → S. aureus. Gram-positive cocci in chains → streptococci. Mixed flora with Gram-negative rods → polymicrobial with anaerobes. Culture + sensitivity guides antibiotic therapy |
| Fine needle aspiration (FNA) of the parotid gland | FNA of swollen parotid gland extra-orally is the best method to identify causative organisms [2]. Performed under ultrasound guidance if needed | Provides material for Gram stain, culture (aerobic + anaerobic), and AFB stain/culture (if TB suspected). Also provides cytology to exclude neoplasm |
| Oral cavity culture caveat | Culture obtained from oral cavity should be interpreted with caution since the results may represent contamination by oral flora [2] | The oral cavity is non-sterile — commensal organisms will always grow. Only duct-expressed pus or direct FNA aspirate gives reliable results |
FNA — Dual Purpose
FNA of the parotid gland serves two purposes: (1) Microbiological — identifying the causative organism in suppurative parotitis, and (2) Cytological — distinguishing benign from malignant pathology if a neoplasm is suspected. FNA can usually discriminate benign tumours from malignant tumours and metastasis but is less specific in the exact type of tumour [11]. Always send aspirate for both microbiology AND cytology when the diagnosis is uncertain.
4. Imaging Investigations
Ultrasound is the first-line investigation for salivary gland pathology [15]:
| Capability | Detail |
|---|---|
| Confirm origin of mass | Is the swelling arising from the parotid gland, submandibular gland, lymph node, or other structure? This is the key first question [15] |
| Stones | Sialoliths appear as hyperechoic foci with posterior acoustic shadowing. US has > 90% sensitivity for stones > 2mm [15] |
| Dilated ducts | Upstream ductal dilatation proximal to an obstruction confirms obstructive pathology [15] |
| Enlarged neck lymph nodes | Reactive vs. suspicious lymphadenopathy can be assessed (shape, hilum, vascularity, cortical thickness) [15] |
| Abscess detection | Hypoechoic or anechoic collection within the gland with posterior acoustic enhancement suggests abscess formation |
| Guidance for FNA | Real-time US guidance improves accuracy and safety of FNA/core biopsy |
| Differentiate solid vs. cystic | Solid mass → neoplasm or inflammatory mass. Cystic → benign cyst, lymphoepithelial cyst (HIV), abscess |
Why ultrasound first?
- Non-invasive, no radiation, inexpensive, widely available, excellent for superficial structures like salivary glands
- Can be performed at the bedside in a sick post-operative patient
- Allows simultaneous FNA under guidance
- Limitation: cannot adequately visualize deep lobe of parotid (obscured by the mandible) or parapharyngeal extension — this is where CT/MRI is needed
CT scan/CT sialogram [16]:
| Capability | Detail |
|---|---|
| Delineate deep lobe vs. superficial lobe tumour | CT can image beyond the mandible to visualize the deep lobe and its relationship to the parapharyngeal space — something ultrasound cannot do [16] |
| Differentiate salivary gland swelling vs. other pathologies | Clearly shows whether the mass arises from the parotid, parapharyngeal space, masticator space, or is a cervical lymph node [16] |
| Enlarged lymph nodes | Cervical lymphadenopathy assessment for staging or reactive adenopathy [16] |
| Abscess detection | CT with IV contrast is the investigation of choice when abscess is suspected (rim-enhancing collection within or adjacent to the gland). This is the key investigation when there is no clinical improvement after 48 hours of IV antibiotics [2] |
| Sialolithiasis | CT is the most sensitive imaging modality for detecting salivary calculi (calcium-dense stones are readily visible) — sensitivity > 95% |
| CT sialogram | Contrast injected retrogradely into the duct → outlines the ductal anatomy, strictures, filling defects (stones), sialectasis (punctate/globular dilatation in Sjögren's). Less commonly used now (replaced by MR sialography and sialendoscopy) |
| Bone involvement | Can detect osteomyelitis of adjacent facial bones (a complication of severe parotitis) [2] |
When to get a CT?
- Suspected abscess (no response to 48 hours of IV antibiotics)
- Suspected deep lobe pathology or parapharyngeal extension
- Pre-operative planning for parotid surgery
- Suspected malignancy (staging)
- MRI/CT parotid and USG FNA — if parotid lesion is suspected [17]
| Capability | Detail |
|---|---|
| Superior soft tissue contrast | MRI provides the best soft tissue delineation of the parotid gland, facial nerve, and surrounding structures |
| Deep lobe and parapharyngeal space | Excellent for assessing deep lobe tumours and their relationship to the parapharyngeal space |
| Perineural spread | MRI is the modality of choice for detecting perineural invasion (especially along CN VII) in malignant parotid tumours — shows thickening and enhancement of the nerve |
| Differentiate benign from malignant | Benign tumours: well-defined, homogeneous. Malignant tumours: ill-defined margins, heterogeneous signal, invasion of adjacent structures |
| MRI/CT parotid and USG FNA — if parotid lesion is suspected [17] | Used when a parotid mass raises concern for neoplasm |
| MR sialography | Non-invasive alternative to conventional sialography. Uses heavily T2-weighted sequences (the saliva in the ducts acts as natural contrast). Shows ductal anatomy, strictures, stones, sialectasis |
When to get an MRI?
- Suspected parotid tumour (especially for surgical planning — relationship to facial nerve)
- Suspected perineural spread of malignancy
- Suspected intracranial extension
- Chronic/recurrent parotitis where Sjögren's or structural abnormality is suspected (MR sialography)
USG/sialogram — rule out stones/other masses in chronic sialadenitis [13]:
- Contrast medium (usually water-soluble) is injected retrogradely into Stensen's or Wharton's duct via a cannula, then X-rays are taken
- Shows: filling defects (stones), strictures, ductal dilatation, sialectasis (classic "cherry blossom" or "snowstorm" appearance in Sjögren's — punctate sialectasis), ductal anatomy
- Contraindicated in acute infection (risk of exacerbating infection and causing bacteraemia)
- Increasingly replaced by MR sialography and sialendoscopy
- Minimally invasive endoscopic technique — a tiny endoscope (0.8–1.6 mm) is inserted into the salivary duct
- Allows direct visualization of the ductal lumen
- Both diagnostic (see stones, strictures, mucous plugs) and therapeutic (basket extraction of stones, balloon dilatation of strictures, irrigation)
- Particularly useful for sialolithiasis and recurrent chronic sialadenitis
- Advantage over sialography: no radiation, therapeutic capability
| Investigation | Indication | Key Points |
|---|---|---|
| FNA cytology | Any parotid mass where neoplasm is suspected [11] | FNA can usually discriminate benign tumours from malignant tumours and metastasis but is less specific in the exact type of tumour [11]. Quick, safe, can be done under US guidance. Send for cytology + microbiology |
| Core needle biopsy | When FNA is non-diagnostic or more tissue architecture is needed (e.g., lymphoma subtyping) | Core needle biopsy has risks of bleeding, nerve injury, and tumour seeding [11]. Provides tissue architecture and allows immunohistochemistry |
| Lip biopsy (minor salivary gland biopsy) | Suspected Sjögren's syndrome | Harvests minor salivary glands from the inner lower lip. Positive if focus score ≥ 1 (≥ 1 focus of ≥ 50 lymphocytes per 4 mm² of glandular tissue). This is a key diagnostic criterion for Sjögren's |
| Incisional/excisional biopsy | Generally avoided for parotid masses (risk of facial nerve damage, tumour seeding, field contamination) | Open biopsy of the parotid is discouraged — definitive surgical excision (superficial parotidectomy) is preferred as both diagnostic and therapeutic for suspected tumours. Exception: when FNA/core biopsy suggests lymphoma and further tissue is needed for subtyping [11] |
Never Do an Incisional Biopsy of a Parotid Mass
Open biopsy of a parotid mass is strongly discouraged because: (1) the facial nerve is at risk, (2) tumour seeding along the biopsy tract can occur, and (3) it makes subsequent definitive surgery more difficult due to scarring and field contamination. The standard approach is FNA (or core biopsy) for tissue diagnosis, followed by formal parotidectomy if indicated [11].
| Aetiology | Specific Investigation | Key Finding |
|---|---|---|
| Mumps | Serology (Mumps IgM, paired IgG); PCR (saliva/urine) | IgM positive in acute infection; PCR confirms active viral shedding |
| Sjögren's syndrome | Anti-Ro/SSA, Anti-La/SSB, ANA, RF; Schirmer test; lip biopsy; MR sialography | Anti-Ro positive in ~70%, Anti-La in ~40%. Schirmer test < 5mm/5min = dry eyes. Lip biopsy focus score ≥ 1. MR sialogram shows punctate/globular sialectasis |
| Sarcoidosis | Serum ACE; CXR (bilateral hilar lymphadenopathy); tissue biopsy (non-caseating granulomas); serum calcium | ACE elevated in ~60%. Biopsy is diagnostic (non-caseating granulomas without AFB) |
| TB parotitis | AFB smear/culture; GeneXpert MTB/RIF; tissue biopsy (caseating granulomas); tuberculin skin test/IGRA | Especially relevant in Hong Kong (intermediate TB prevalence). Caseating granulomas distinguish from sarcoidosis |
| HIV | HIV antibody/antigen test (4th generation combo); CD4 count; viral load | Consider in bilateral painless parotid enlargement, especially with cystic lesions on imaging (lymphoepithelial cysts) |
| IgG4-related disease | Serum IgG4; tissue biopsy (storiform fibrosis, obliterative phlebitis, IgG4+ plasma cells > 10/HPF) | Elevated serum IgG4 (though sensitivity is only ~60–70%). Biopsy is the gold standard |
| Sialolithiasis | CT (gold standard for stone detection); US; sialography; sialendoscopy | CT: hyperdense calculus within duct/gland. US: hyperechoic focus with acoustic shadow + dilated duct upstream |
| Clinical Scenario | First-Line | Second-Line | Microbiological | Specific |
|---|---|---|---|---|
| Acute suppurative parotitis | Clinical examination (express pus) + bloods (CBC, CRP, amylase) | CT with contrast (if abscess suspected / no response to Abx at 48 hrs) | Gram stain + C/S of expressed pus; FNA if no pus expressible; blood cultures | — |
| Viral parotitis | Clinical diagnosis | — | — | Mumps serology (IgM/IgG); Mumps PCR |
| Sialolithiasis | Ultrasound — first line [15] | CT (most sensitive for stones); sialography/sialendoscopy | — | — |
| Chronic sialadenitis | USG/sialogram [13] | MR sialography; sialendoscopy | — | Rule out Sjögren's syndrome [13] |
| Suspected neoplasm | Ultrasound — first line + FNA [15][17] | MRI (best for surgical planning, perineural spread); CT [16][17] | — | FNA cytology or core needle biopsy [11] |
| Bilateral painless enlargement | Bloods (TFTs, HbA1c, LFTs, autoimmune serology, HIV test) + US | MRI if structural abnormality suspected | — | Lip biopsy (Sjögren's); serum ACE (sarcoidosis); serum IgG4 |
High Yield Summary
- Diagnosis of acute suppurative parotitis is clinical: sick patient + unilateral tender parotid swelling + pus from Stensen's duct + elevated amylase (with normal lipase)
- Ultrasound is the first-line investigation for any salivary gland pathology — confirms origin, detects stones, dilated ducts, lymph nodes, and can guide FNA
- FNA of the swollen parotid gland extra-orally is the best method to identify causative organisms in suppurative parotitis
- Elevated serum amylase in the absence of pancreatitis supports parotid involvement — check lipase to exclude pancreatitis
- CT with contrast is indicated when abscess is suspected (no improvement after 48 hours of IV antibiotics) or to assess deep lobe/parapharyngeal extension
- MRI is the gold standard for parotid tumour assessment (facial nerve relationship, perineural spread)
- Viral parotitis is diagnosed by clinical presentation and serology — no pus from duct, often bilateral, self-limiting
- Culture from oral cavity should be interpreted with caution — contamination by oral flora is inevitable; duct-expressed pus or FNA aspirate is more reliable
- Never do an open incisional biopsy of a parotid mass — use FNA or core biopsy, then proceed to formal parotidectomy if needed
- For chronic/bilateral parotid enlargement, investigate for Sjögren's (SSA/SSB, lip biopsy), sarcoidosis (ACE, CXR), DM, hypothyroidism, HIV, IgG4-RD, and drug history
Active Recall - Diagnosis and Investigations of Parotitis
References
[1] Lecture slides: GC 217. Facial nerve palsy and salivary gland diseases.pdf, p50 [2] Senior notes: felixlai.md, sections 321–323 [3] Lecture slides: GC 217. Facial nerve palsy and salivary gland diseases.pdf, p51 [7] Lecture slides: GC 217. Facial nerve palsy and salivary gland diseases.pdf, p41 [10] Lecture slides: GC 217. Facial nerve palsy and salivary gland diseases.pdf, p53 [11] Senior notes: felixlai.md, section 336 [13] Lecture slides: GC 217. Facial nerve palsy and salivary gland diseases.pdf, p54 [14] Lecture slides: GC 217. Facial nerve palsy and salivary gland diseases.pdf, p40 [15] Lecture slides: GC 217. Facial nerve palsy and salivary gland diseases.pdf, p43 [16] Lecture slides: GC 217. Facial nerve palsy and salivary gland diseases.pdf, p46 [17] Lecture slides: GC 217. Facial nerve palsy and salivary gland diseases.pdf, p11
Management of Parotitis
The management of parotitis depends entirely on the aetiology. The overarching principles are:
- Treat the cause (antibiotics for bacterial, supportive for viral, remove stones for obstructive, immunosuppression for autoimmune)
- Reverse predisposing factors (rehydrate, improve oral hygiene, stop offending drugs)
- Manage complications (drain abscesses, secure airway if threatened, address sepsis)
- Prevent recurrence (address underlying risk factors, consider gland excision for recurrent disease)
Think of it as a stepwise approach: supportive measures first → medical treatment → surgical treatment if medical fails.
These are the foundation of management regardless of aetiology. The rationale for each is rooted in the pathophysiology:
| Measure | Rationale / Mechanism |
|---|---|
| Rehydration (IV fluids in acute setting) [1] | Dehydration is the single most important predisposing factor. Rehydration restores salivary flow, which re-establishes the mechanical flushing action that clears bacteria from the ductal system. In post-operative patients, ensure adequate IV fluid replacement and encourage oral intake as early as possible |
| Oral hygiene | Poor oral hygiene increases the bacterial load in the oral cavity — the source of retrograde infection. Chlorhexidine mouthwashes reduce oral bacterial colonization. Regular tooth brushing and oral care (especially in intubated/ICU patients) |
| Warm compresses + massage [18] | External warm compresses promote vasodilation → improved blood flow to the gland → enhanced immune cell delivery and oedema resorption. Gentle massage of the gland (from posterior to anterior, towards the duct) promotes forward drainage of stagnant, infected secretions through Stensen's duct |
| Sialogogues [18] | Sialogogues ("sialon" = saliva, "agogos" = leading/promoting) are agents that stimulate salivary flow. Examples: sour candy, lemon drops, vitamin C tablets, pilocarpine (muscarinic agonist). By increasing salivary flow, they flush bacteria and debris out through the duct — essentially restoring the gland's own defence mechanism. Pilocarpine (5 mg TDS) is a parasympathomimetic that directly stimulates M3 muscarinic receptors on salivary acinar cells |
| Analgesia | Paracetamol and/or NSAIDs for pain control. NSAIDs (e.g., ibuprofen) also provide anti-inflammatory benefit. Avoid aspirin in children with viral parotitis (risk of Reye syndrome) |
| Heat application [18] | Local warmth promotes vasodilation and helps liquify inspissated secretions within the duct, facilitating drainage |
| Discontinue offending drugs | If anticholinergics (atropine, glycopyrrolate, antihistamines, tricyclics) are contributing to xerostomia, consider alternatives where clinically possible. Similarly review diuretics that may be contributing to dehydration |
The Mnemonic for Conservative Parotitis Management: SHAMS
- S — Sialogogues (lemon drops, pilocarpine)
- H — Hydration (IV fluids + oral fluids)
- A — Antibiotics (if bacterial)
- M — Massage (gland massage to promote drainage)
- S — Stop offending drugs (anticholinergics) + warm compresses (Steam/heat)
Antibiotic Therapy
Antibiotics are the cornerstone of treatment for bacterial suppurative parotitis. The choice reflects the expected microbiology: S. aureus is the most common organism [1], with polymicrobial infection (including oral streptococci and anaerobes) being frequent [2].
Total duration = 10–14 days [2]
Empiric Regimens
1. Immunocompetent host [2]:
| Component | Drug Options | Rationale |
|---|---|---|
| Anti-staphylococcal agent | Nafcillin OR 1st generation cephalosporin (e.g., cefazolin IV → cephalexin PO) | Nafcillin ("naf-" = nafcillin is a penicillinase-resistant penicillin) — specifically targets S. aureus including penicillinase-producing strains. 1st gen cephalosporins (cefazolin) also have excellent Gram-positive cover including MSSA |
| PLUS anaerobic cover | Clindamycin OR Metronidazole | The infection is often polymicrobial with oral anaerobes (Bacteroides, Fusobacterium, Prevotella, Peptostreptococcus). Clindamycin covers both Gram-positive cocci AND anaerobes (dual purpose — can sometimes be used as monotherapy). Metronidazole ("metro-" = metrum/womb, but think of it as the quintessential anaerobe killer) covers only anaerobes — must be combined with anti-staphylococcal agent |
Practical tip: In Hong Kong, a common empiric regimen is IV Augmentin (amoxicillin-clavulanate) which covers S. aureus (MSSA), streptococci, AND anaerobes in a single agent. This is a reasonable empiric choice for community-acquired suppurative parotitis in immunocompetent patients. If MRSA prevalence is high or the patient is hospital-acquired, broader cover is needed.
2. Immunocompromised host [2]:
| Component | Drug Options | Rationale |
|---|---|---|
| MRSA cover | Vancomycin OR Linezolid | Immunocompromised patients are at higher risk for MRSA and resistant organisms. Vancomycin ("vanco-" = "vanquish") is the gold standard for MRSA. Linezolid is an alternative (oxazolidinone — inhibits ribosomal 50S subunit) with excellent tissue penetration and oral bioavailability |
| PLUS broad Gram-negative + anaerobic cover | Cefepime OR Imipenem OR Meropenem OR Piperacillin-tazobactam | Immunocompromised patients are at risk for Gram-negative organisms (Pseudomonas, Enterobacteriaceae) in addition to Gram-positives and anaerobes. These agents provide broad-spectrum cover: Cefepime (4th gen cephalosporin — anti-Pseudomonal); Carbapenems (imipenem/meropenem — broadest spectrum); Pip-tazo (anti-Pseudomonal penicillin + β-lactamase inhibitor). All also cover anaerobes |
Why Broader Cover in Immunocompromised?
In immunocompetent patients, the immune system helps contain infection and the flora is predictable (S. aureus + oral flora). In immunocompromised patients (HIV, chemotherapy, transplant, uncontrolled DM), the immune system cannot restrict bacterial proliferation, so more virulent and resistant organisms (MRSA, Pseudomonas, Enterobacteriaceae) can establish infection. You need antibiotics that cover the worst-case scenario because you cannot rely on the immune system to do its share of the work.
Antibiotic Step-Down
- Start IV → when the patient is afebrile for 24–48 hours, improving clinically, and tolerating oral intake, step down to oral antibiotics to complete the total 10–14 day course
- Oral step-down options:
- Immunocompetent: Oral cephalexin + metronidazole, OR oral amoxicillin-clavulanate (Augmentin), OR oral clindamycin
- Immunocompromised: Guided by culture and sensitivity results
Adjusting Antibiotics Based on Culture Results
- Once Gram stain and culture/sensitivity results return (from expressed pus or FNA), narrow the antibiotic spectrum to target the identified organism(s)
- This is the principle of antibiotic stewardship — start broad empirically, narrow once you know the enemy
C. Surgical Treatment
Incision and drainage (I&D) is indicated when there is no clinical response after 48 hours of treatment with empiric intravenous antibiotics [2]
| Aspect | Detail |
|---|---|
| Indication | Failure to improve after 48 hours of appropriate IV antibiotics, OR clinical/imaging evidence of discrete abscess formation (fluctuance on exam; rim-enhancing collection on CT with contrast) [2] |
| Pre-operative imaging | CT with IV contrast to confirm abscess, delineate its location (superficial vs. deep lobe), and plan the surgical approach |
| Surgical approach | Modified Blair incision (pre-auricular extending to submandibular) — the same incision used for parotidectomy. The dissection must be performed carefully with identification and preservation of the facial nerve (CN VII), as the nerve runs through the gland. Pus is drained, loculations are broken down, and the cavity is irrigated. A drain is typically left in situ |
| Key risk | Facial nerve injury — the facial nerve divides the parotid into superficial and deep lobes and branches within the gland. Incision into the parotid without identifying the nerve can cause permanent facial palsy. This is why abscess drainage should be performed by an experienced surgeon (ideally ENT or maxillofacial) |
| Alternative for small/superficial abscess | US-guided needle aspiration — less invasive, can be repeated, avoids the risk of facial nerve injury from formal I&D. Appropriate for small, well-defined, superficial collections |
| Post-operative care | Continue IV antibiotics, send pus for culture, wound care, monitor for facial nerve function |
Why 48 hours as the threshold? Most acute bacterial parotitis will begin to show clinical improvement (reduced fever, decreased swelling and tenderness) within 24–48 hours of appropriate IV antibiotics. If there is no improvement by 48 hours, this suggests either: (1) an undrained abscess that antibiotics cannot penetrate (antibiotics don't work well against walled-off pus collections — you need source control), (2) resistant organisms, or (3) an alternative/missed diagnosis.
The management of sialolithiasis follows a stepwise approach from conservative to increasingly interventional [18][19]:
Sialolithiasis treatment [19]:
| Step | Treatment | Indication / Detail |
|---|---|---|
| Step 1: Conservative | Conservative — small stones to pass by themselves [19]. Hydration, sialogogues (lemon drops), massage, warm compresses | Small stones ( < 5 mm), mobile stones near the duct orifice. The rationale is to increase salivary flow to "flush" the stone out naturally. Many small stones will pass spontaneously |
| Step 2: Transoral removal | Transoral removal/excision [19] | For stones palpable in the distal portion of Stensen's or Wharton's duct (near the duct opening). Under local anaesthesia, an incision is made directly over the stone through the oral mucosa, the stone is removed, and the duct is marsupialised to prevent stenosis |
| Step 3: Sialendoscopy | Sialendoscopy and removal [19] | For stones that are not accessible transorally but are within the ductal system. A miniature endoscope (0.8–1.6 mm) is introduced into the duct orifice. The stone is visualised and removed using a basket/forceps, or fragmented with intracorporeal lithotripsy (laser). Both diagnostic and therapeutic. Minimally invasive with gland preservation |
| Step 4: Gland excision | Excision of the gland [19] | Indications: proximal stone — inaccessible by scope or transoral excision; recurrent stones; multiple stones [19]. For the submandibular gland: submandibular gland excision (via transcervical approach). For the parotid gland: superficial parotidectomy (requires identification and preservation of CN VII). Gland excision is the definitive treatment when conservative and minimally invasive methods fail |
Sialadenitis treatment (general principles for any sialadenitis) [18]:
- Hydration
- Sialogogues, massage, heat, antibiotics during acute attacks
- Remove stones [18]
- Exploration of submandibular duct
- Sialendoscopy
- Excision of the gland (for recurrent chronic sialadenitis) [18]
Viral parotitis is self-limiting — there is no specific antiviral therapy for mumps. Management is entirely supportive [3]:
| Measure | Detail |
|---|---|
| Bed rest | Reduces energy expenditure during acute viraemia |
| Adequate hydration | Oral fluids primarily; IV fluids if unable to drink (severe trismus/dysphagia) |
| Analgesics | Paracetamol and/or NSAIDs. Avoid aspirin in children (risk of Reye syndrome — acute hepatic encephalopathy associated with aspirin use during viral illness) |
| Warm or cool compresses | Symptomatic relief of pain and swelling |
| Avoid acidic/sour foods | These stimulate salivary flow, which increases pain in the inflamed gland (distension against oedematous parenchyma) |
| Isolation | Mumps is a notifiable disease in Hong Kong. The patient is infectious from ~2 days before parotid swelling to ~5 days after onset. Standard and droplet precautions. Exclude from school/work for 5 days after parotid onset |
| Monitor for complications | Orchitis (testicular pain/swelling — 15–30% of post-pubertal males), meningitis (headache, neck stiffness, photophobia), pancreatitis (epigastric pain, vomiting, raised amylase/lipase), sensorineural hearing loss (usually unilateral), encephalitis (rare but serious) |
Avoid ampicillin in EBV infectious mononucleosis (which can also cause parotid enlargement) — it causes a characteristic rubelliform rash in ~90% of patients with EBV who receive ampicillin/amoxicillin [20]. This is not a true allergy but an immune-mediated reaction. Always consider EBV when prescribing antibiotics for sore throat with bilateral parotid/cervical swelling.
Mumps Vaccination — Prevention Is Better Than Cure
The MMR vaccine (live attenuated) is the best prevention. In Hong Kong, it is given at age 1 and age 6 (Primary 1). Two doses provide ~88% efficacy against mumps. Outbreaks still occur in under-vaccinated populations. Post-exposure prophylaxis with MMR vaccine is not reliably effective but may be offered to unvaccinated contacts.
If parotitis extends to cause a parapharyngeal abscess or other deep neck space infection, the management principles are [21]:
- Secure airway — deep neck infections can rapidly compromise the airway through pharyngeal/laryngeal oedema [21]
- Surgical drainage — deep neck abscesses require formal surgical drainage (transcervical approach); antibiotics alone are insufficient for walled-off collections [21]
- IV antibiotics — broad-spectrum empiric cover (similar to immunocompromised regimen: vancomycin + piperacillin-tazobactam or carbapenem) pending cultures [21]
- Dental consultation — if an odontogenic source is suspected [21]
F. Management of Chronic / Autoimmune Parotitis
- Symptomatic: Artificial tears (for keratoconjunctivitis sicca), saliva substitutes, sialogogues (pilocarpine 5 mg TDS or cevimeline)
- Systemic treatment: Hydroxychloroquine for arthralgias and fatigue; rituximab for severe systemic disease; mycophenolate or azathioprine for major organ involvement
- Monitor for lymphoma (40-fold increased risk of non-Hodgkin B-cell lymphoma) — any rapidly enlarging parotid mass in a Sjögren's patient warrants urgent FNA/biopsy
- Mild disease: observation (may resolve spontaneously)
- Moderate-severe: systemic corticosteroids (prednisolone); steroid-sparing agents (methotrexate, azathioprine) for refractory disease
- Conservative: hydration, sialogogues, massage during acute episodes, short-course antibiotics if superinfected
- Usually self-limiting — resolves by puberty
- Sialendoscopy with ductal irrigation (steroid lavage) can reduce frequency of recurrences
- Parotidectomy very rarely needed (reserved for truly refractory cases)
| Strategy | Detail |
|---|---|
| Perioperative hydration | Adequate IV fluid resuscitation in surgical patients is the single most important preventive measure for post-operative parotitis. Encourage early oral intake |
| Oral hygiene in hospitalised patients | Regular mouth care (tooth brushing, chlorhexidine mouth rinses) — especially in ICU/intubated patients |
| Minimise anticholinergics | Use alternative drugs where possible; if anticholinergics are essential, ensure the patient is well-hydrated |
| MMR vaccination | For mumps prevention — two doses (age 1 and age 6 in HK) |
| Sialendoscopy / stone removal | In patients with recurrent obstructive parotitis, definitive stone management prevents recurrent infection |
| Aetiology | Supportive | Medical | Surgical | Duration / Notes |
|---|---|---|---|---|
| Acute suppurative | Rehydration, IV antibiotics [1], oral hygiene, warm compress, massage, sialogogues, analgesia | Empiric IV Abx → step down to PO. Immunocompetent: nafcillin/cephalosporin + clindamycin/metronidazole. Immunocompromised: vancomycin/linezolid + cefepime/carbapenem/pip-tazo [2] | I&D if no response after 48 hrs of IV Abx [2] | 10–14 days total [2] |
| Viral (mumps) | Bed rest, hydration, analgesics (avoid aspirin in children), warm/cool compresses | None (self-limiting) | Not indicated | 5–10 days; isolation; notify CHP |
| Sialolithiasis | Hydration, sialogogues, massage, heat [18] | Abx if superinfected [18] | Conservative → transoral removal → sialendoscopy → gland excision [19] | Stepwise approach |
| Chronic sialadenitis | Hydration, sialogogues, massage, heat [18] | Abx during acute flares [18] | Remove stones; sialendoscopy; gland excision for recurrent disease [18] | Treat underlying cause (Sjögren's, etc.) |
| Parotid abscess | As for suppurative | Continue IV Abx | I&D (formal or US-guided aspiration) [2] | Surgical drainage is essential |
| Deep neck abscess | Secure airway [21] | IV antibiotics [21] | Surgical drainage [21] | Multidisciplinary (ENT + anaesthesia) |
| Treatment | Contraindication / Caution |
|---|---|
| Sialography (for chronic sialadenitis workup) | Contraindicated in acute infection — retrograde injection of contrast during active infection can exacerbate the infection and cause bacteraemia |
| Aspirin (as analgesia) | Contraindicated in children with viral parotitis — risk of Reye syndrome |
| Ampicillin/amoxicillin | Avoid in EBV infectious mononucleosis — causes characteristic rubelliform rash [20]. If unsure whether the parotitis is mumps vs. EBV, avoid these drugs until EBV is excluded |
| Incisional/open biopsy of parotid | Strongly discouraged — risk of facial nerve injury, tumour seeding, field contamination. Use FNA or core biopsy instead [11] |
| Pilocarpine (sialogogue) | Caution in patients with uncontrolled asthma (parasympathomimetic → bronchoconstriction), narrow-angle glaucoma (pupillary constriction may precipitate angle closure in susceptible individuals), or bradycardia |
| Parotidectomy | Requires experienced surgeon (ENT/maxillofacial). Risk of CN VII injury (temporary ~20%, permanent ~3–5%), Frey syndrome (gustatory sweating — post-surgical aberrant reinnervation of auriculotemporal nerve to sweat glands), haemorrhage, salivary fistula, first bite syndrome |
Frey Syndrome — A Unique Surgical Complication
After parotidectomy, the severed parasympathetic secretomotor fibres (intended for the parotid gland) can aberrantly regenerate and innervate the sweat glands of the overlying skin. This results in gustatory sweating — the patient sweats over the parotid region during eating. It occurs in up to 30–60% of patients after parotidectomy. Treatment: topical antiperspirant, botulinum toxin injection, interposition graft (e.g., AlloDerm or superficial musculoaponeurotic system flap) at the time of surgery.
High Yield Summary
- Acute suppurative parotitis: Rehydration + IV antibiotics [1]. Duration 10–14 days [2]. Immunocompetent: anti-staphylococcal + anaerobic cover. Immunocompromised: MRSA cover + broad Gram-negative/anaerobic cover
- I&D is indicated when no clinical response after 48 hours of IV antibiotics [2] — always get CT first to confirm abscess
- Viral parotitis (mumps): supportive only — bed rest, hydration, analgesia. Self-limiting 5–10 days. No antiviral needed. Notifiable disease
- Sialolithiasis: stepwise — conservative (small stones pass) → transoral removal → sialendoscopy → gland excision [19] if proximal/recurrent/multiple stones
- Chronic sialadenitis: hydration, sialogogues, massage, heat, antibiotics during acute attacks, remove stones, gland excision if recurrent [18]
- Deep neck abscess: secure airway → surgical drainage → IV antibiotics [21]
- Prevention of post-operative parotitis: adequate perioperative hydration + oral hygiene — this is the single most effective preventive strategy
- Key contraindications: no sialography in acute infection; no aspirin in children with viral illness; avoid ampicillin in EBV
- Frey syndrome: gustatory sweating post-parotidectomy due to aberrant parasympathetic reinnervation of skin sweat glands
Active Recall - Management of Parotitis
References
[1] Lecture slides: GC 217. Facial nerve palsy and salivary gland diseases.pdf, p50 [2] Senior notes: felixlai.md, section 323 [3] Lecture slides: GC 217. Facial nerve palsy and salivary gland diseases.pdf, p51 [11] Senior notes: felixlai.md, section 336 [18] Lecture slides: GC 217. Facial nerve palsy and salivary gland diseases.pdf, p55 [19] Lecture slides: GC 217. Facial nerve palsy and salivary gland diseases.pdf, p57 [20] Lecture slides: GC 219. Infections and tumours in pharynx and oral cavity.pdf, p15 [21] Lecture slides: GC 219. Infections and tumours in pharynx and oral cavity.pdf, p22
Complications of Parotitis
Complications of parotitis can be divided into those arising from the disease itself (infectious parotitis — bacterial or viral) and those arising from surgical treatment (parotidectomy or I&D). Understanding the anatomy of the parotid region is the key to understanding why each complication occurs — every single one can be traced back to the intimate relationships between the parotid gland and its neighbours.
A. Complications of Parotitis (The Disease)
Complications of parotitis [2]:
| Aspect | Detail |
|---|---|
| Mechanism | The deep lobe of the parotid gland is intimately related to the parapharyngeal space, which forms the lateral wall of the oropharynx. Severe parotid swelling — particularly bilateral or deep lobe involvement — can cause extrinsic compression and oedema of the pharyngeal/laryngeal airway. If infection extends into the parapharyngeal space (forming a parapharyngeal abscess), the pharyngeal wall bulges medially, critically narrowing the airway. Additionally, a large parotid abscess can cause trismus so severe that the patient cannot open their mouth, compromising oral airway access |
| Clinical features | Stridor (inspiratory — suggests supraglottic narrowing), dyspnoea, drooling (unable to swallow secretions), "hot potato" voice (muffled voice from pharyngeal oedema), tripod positioning |
| Management | Secure airway — this is the first priority before anything else. May require fibreoptic intubation or surgical airway (cricothyroidotomy/tracheostomy) if oral intubation is impossible due to trismus. Then proceed with surgical drainage + IV antibiotics [21] |
Airway First!
In any deep neck space infection — whether from parotitis, peritonsillar abscess, or odontogenic infection — airway management takes precedence over everything. A patient can die from airway obstruction within minutes. Always assess and secure the airway before proceeding to imaging or definitive surgical drainage.
| Aspect | Detail |
|---|---|
| Mechanism | The facial nerve (CN VII) exits the stylomastoid foramen and traverses through the substance of the parotid gland, dividing into its 5 terminal branches (temporal, zygomatic, buccal, marginal mandibular, cervical) within it. Severe parotid inflammation, oedema, or abscess formation can compress the nerve within the tight fascial capsule. Direct neuritis (inflammatory infiltration of the nerve) can also occur. If a parotid abscess erodes into the nerve trunk, irreversible damage results |
| Clinical features | Lower motor neuron (LMN) facial palsy — weakness of the entire ipsilateral half of the face (forehead AND lower face), in contrast to UMN lesions which spare the forehead. Inability to close the eye (zygomatic branch), loss of nasolabial fold (buccal branch), drooping mouth corner (marginal mandibular branch). May be partial (affecting only some branches) depending on the location and extent of nerve involvement |
| Why LMN? | The lesion is at the level of the nerve trunk or its branches within the parotid gland — this is distal to the facial motor nucleus in the pons, so it is a peripheral (LMN) pattern. In UMN lesions (e.g., stroke), the forehead is spared because the upper face receives bilateral cortical innervation |
| Prognosis | If due to oedema/compression alone → usually reversible with treatment of the infection. If due to direct nerve destruction by abscess → may be permanent. Early aggressive treatment of parotitis (antibiotics ± drainage) is the best way to prevent this complication |
| Important distinction | Facial nerve palsy occurring with a parotid mass (rather than acute infection) is a red flag for malignancy — malignant tumours invade the nerve perineurally, whereas benign tumours merely displace it [11] |
| Aspect | Detail |
|---|---|
| Mechanism | Bacteria from the suppurative parotid gland enter the bloodstream via the rich venous drainage of the gland (retromandibular vein → external/internal jugular system). The parotid's extensive vascular supply, combined with the virulence of organisms like S. aureus, facilitates haematogenous dissemination. In debilitated, immunocompromised, or elderly patients, the impaired immune response allows unchecked bacterial proliferation and systemic spread |
| Clinical features | High spiking fevers, rigors, tachycardia, hypotension, altered mental status — the full spectrum of systemic inflammatory response syndrome (SIRS) → sepsis → septic shock. End-organ dysfunction (acute kidney injury, coagulopathy, hepatic dysfunction) may develop |
| Risk factors | Delayed treatment, immunocompromised host, very elderly, already debilitated patients (the exact population that develops parotitis in the first place) |
| Investigations | Blood cultures (at least 2 sets from different sites before antibiotics), serum lactate, procalcitonin, full sepsis workup |
| Management | Aggressive IV fluid resuscitation, broad-spectrum IV antibiotics (escalate to immunocompromised regimen: vancomycin + piperacillin-tazobactam or carbapenem), source control (I&D if abscess), vasopressors if refractory hypotension, ICU admission |
| Aspect | Detail |
|---|---|
| Mechanism | The deep lobe of the parotid gland is separated from the parapharyngeal space by only a thin fascial layer. Infection from the parotid can track directly through this fascia into the parapharyngeal space (a potential space lateral to the pharynx, bounded by the superior pharyngeal constrictor medially and the pterygoid muscles/mandible laterally). The parapharyngeal space also communicates with the retropharyngeal space, submandibular space, and masticator space — so infection can spread widely through fascial planes |
| Clinical features | Fever, severe sore throat, dysphagia, odynophagia, trismus, "hot potato" voice, neck swelling/induration. On intraoral exam: medial bulging of the lateral pharyngeal wall (pushing the tonsil medially) |
| Danger | The parapharyngeal space contains the internal carotid artery, internal jugular vein, and cranial nerves IX, X, XI, XII. Infection in this space can erode into the carotid (catastrophic haemorrhage), spread to the mediastinum via the retropharyngeal space (descending necrotising mediastinitis — a life-threatening emergency), or cause septic jugular thrombophlebitis |
| Management | CT with contrast to delineate the abscess → secure airway → surgical drainage (transcervical approach) → IV antibiotics [21] |
Lemierre's Syndrome (Septic Jugular Thrombophlebitis) [2]
| Aspect | Detail |
|---|---|
| Mechanism | Septic jugular thrombophlebitis occurs when infection from the parapharyngeal space (or directly from the deep parotid) involves the internal jugular vein (IJV). Bacterial invasion of the vein wall triggers thrombosis + seeding of the thrombus with bacteria → infected thrombus → septic emboli disseminate via the venous system to distant sites. Classically associated with Fusobacterium necrophorum (a normal oral anaerobe), though any pathogen can cause it |
| Clinical features | High spiking fevers with rigors that fail to resolve despite antibiotics; tender/indurated neck along the course of the IJV (anterior border of sternocleidomastoid); septic pulmonary emboli (multiple peripheral lung nodules/cavities on CXR or CT thorax — "cannon ball" lesions); may also seed to joints (septic arthritis), liver (hepatic abscesses), bone |
| Investigations | CT neck with contrast (filling defect in IJV = thrombus); CT thorax (septic pulmonary emboli); blood cultures (anaerobes — need to request specifically and hold cultures for > 5 days) |
| Management | Prolonged IV antibiotics (4–6 weeks; must cover anaerobes — metronidazole or clindamycin + broad-spectrum agent); anticoagulation is controversial (some advocate for it to prevent thrombus propagation); surgical drainage of the primary source; IJV ligation in refractory cases is rarely required |
Lemierre's Syndrome — The 'Forgotten Disease'
Lemierre's syndrome was common in the pre-antibiotic era, became rare with antibiotics, but has re-emerged — partly due to more conservative antibiotic prescribing for upper respiratory infections. It classically follows pharyngotonsillitis in young adults but can complicate any deep neck space infection, including parotitis. The triad of recent oropharyngeal/parotid infection + septic clinical picture + septic pulmonary emboli should trigger this diagnosis.
| Aspect | Detail |
|---|---|
| Mechanism | Direct contiguous spread of infection from the parotid gland to the adjacent mandible (ramus of mandible) or temporal bone (mastoid process). The parotid lies directly over the ramus of the mandible and just anterior to the mastoid process. In severe, prolonged, or inadequately treated parotitis — particularly in immunocompromised patients — bacteria can penetrate the periosteum and establish infection within the bone marrow (osteomyelitis). The mandible's relatively poor blood supply (compared to, say, the tibia) makes it somewhat vulnerable once infection reaches the bone |
| Clinical features | Persistent deep bone pain despite treatment of soft tissue infection, chronic draining sinuses, loosening of teeth (if alveolar bone involved), pathological fracture in severe cases. Systemic features may be mild (chronic osteomyelitis) or marked (acute osteomyelitis) |
| Investigations | CT (cortical erosion, periosteal reaction); MRI (bone marrow oedema — most sensitive early finding); bone biopsy + culture for definitive microbiological diagnosis; bone scan (increased uptake — sensitive but non-specific) |
| Management | Prolonged IV antibiotics (minimum 4–6 weeks, guided by bone culture); surgical debridement of necrotic bone if present; address the source (treat the parotitis/abscess); hyperbaric oxygen therapy may be considered as adjunct in refractory cases (promotes angiogenesis and osteoclast/osteoblast activity in poorly vascularised infected bone) |
| Aspect | Detail |
|---|---|
| Mechanism | Contiguous infection or haematogenous seeding to intraparotid or periparotid lymph nodes leads to abscess formation [2]. When bacteria proliferate faster than the immune response can contain them, focal liquefactive necrosis occurs → discrete walled-off pus collection within or adjacent to the gland. The parotid's unique intraglandular lymph nodes can serve as foci for abscess development |
| Clinical features | Persistent or worsening pain and swelling despite 48 hours of IV antibiotics, fluctuance on examination (late sign), persistent high fever, failure of inflammatory markers to downtrend |
| Investigations | CT with IV contrast — rim-enhancing hypodense collection confirms abscess |
| Management | Incision and drainage (or US-guided aspiration for smaller collections) + continue IV antibiotics |
Mumps is usually self-limiting, but complications can affect multiple organ systems due to the virus's tropism for glandular and neural tissue:
| Complication | Mechanism / Explanation | Frequency |
|---|---|---|
| Orchitis/epididymo-orchitis | Mumps virus has tropism for germinal epithelium of the testes. Haematogenous spread → viral replication in testicular cells → inflammation and oedema within the rigid tunica albuginea → ischaemic pressure necrosis of seminiferous tubules. Presents as testicular pain/swelling 4–8 days after parotid onset | 15–30% of post-pubertal males (rare pre-puberty) |
| Subfertility (post-orchitis) | Ischaemic damage to seminiferous tubules → impaired spermatogenesis. Bilateral orchitis (rare — ~15% of those with orchitis) carries the highest risk. Complete sterility is uncommon (~1%) but oligospermia can occur in up to 13% | Uncommon but feared |
| Meningitis (aseptic) | Viral invasion of the meninges → lymphocytic meningitis. CSF shows lymphocytic pleocytosis, elevated protein, normal glucose | Up to 10% (most are subclinical); CSF pleocytosis may be present in > 50% without clinical meningitis |
| Encephalitis | Direct viral invasion of brain parenchyma | Rare (0.1–0.3%); mortality ~1.5% |
| Pancreatitis | Viral tropism for pancreatic acinar cells → inflammation | ~5%; presents with epigastric pain, vomiting, elevated amylase AND lipase (helps distinguish from parotitis-only elevated amylase where lipase is normal) |
| Sensorineural hearing loss | Viral damage to the cochlea (organ of Corti) and/or cochlear nerve → unilateral sensorineural deafness. Usually permanent | ~1 in 20,000 cases; usually unilateral |
| Oophoritis | Ovarian inflammation (analogous to orchitis) | 5% of post-pubertal females; rarely causes infertility (ovarian reserve is more resilient than testicular) |
| Myocarditis | Viral inflammation of myocardium | Rare; usually subclinical ECG changes |
| Arthritis | Immune-mediated reactive arthritis | Rare; large joints, self-limiting |
How to distinguish pancreatitis from parotitis when amylase is elevated: Check lipase. Lipase is elevated ONLY in pancreatitis, not in isolated parotitis. If both amylase and lipase are raised in a mumps patient, they likely have both parotitis AND pancreatitis.
C. Complications of Parotidectomy (Surgical Complications)
If parotitis requires surgical intervention (I&D of abscess, or parotidectomy for recurrent disease or concomitant neoplasm), there are specific surgical complications:
| Complication | Mechanism | Detail |
|---|---|---|
| Bleeding / haematoma [22] | Injury to the rich vascular supply of the parotid region (external carotid artery branches, retromandibular vein). Post-operative reactionary (first 24 hours) or secondary (days 5–10, usually infection-related) haemorrhage | Expanding neck haematoma can compress the airway → surgical emergency requiring urgent re-exploration and evacuation. This is why patients are monitored closely post-operatively with a drain in situ |
| Facial nerve palsy [22] | The facial nerve runs through the parotid gland and must be dissected and preserved during parotidectomy. Even with meticulous technique, the nerve can be injured by direct trauma, traction, electrocautery heat, or post-operative oedema. Transient ~5%; permanent ~1% [22] | Transient palsy is usually due to neuropraxia (oedema/traction) and recovers over weeks to months. Permanent palsy results from axonotmesis or neurotmesis (nerve division). If the nerve is intentionally sacrificed (for malignant tumour encasement), nerve grafting (great auricular nerve or sural nerve graft) can be performed |
| Wound infection [22] | Bacterial contamination of the surgical field | Standard wound infection management: antibiotics, wound care, drainage if collection forms |
| Salivary fistula [22] | Residual parotid tissue continues to produce saliva which leaks through the wound rather than draining via Stensen's duct (if the duct is damaged or the remaining gland is disrupted) | Usually self-limiting — managed with pressure dressings, antisialogogue drugs (e.g., glycopyrrolate to reduce salivary secretion), and botulinum toxin injection to the residual gland in refractory cases |
| Complication | Mechanism | Detail |
|---|---|---|
| Recurrence [23] | Incomplete excision of the primary pathology (particularly relevant for pleomorphic adenoma, which has pseudopod extensions beyond the visible tumour capsule → tumour seeding if capsule is violated) | Pleomorphic adenoma has a ~2–4% recurrence rate after adequate superficial parotidectomy, but much higher (20–45%) after enucleation alone. Recurrent pleomorphic adenoma is multinodular and much harder to treat |
| Frey's syndrome — gustatory sweating [23] | Characterized by sweating and flushing of facial skin over parotid bed and neck during mastication [11]. Results from aberrant regeneration of cut parasympathetic fibres between the otic ganglion and salivary tissues which leads to innervation of sweat glands and subcutaneous vessels [11]. The auriculotemporal nerve (a branch of CN V3 carrying post-ganglionic parasympathetic secretomotor fibres from the otic ganglion to the parotid) is severed during surgery. During nerve regeneration, these parasympathetic fibres aberrantly innervate the sympathetically-controlled sweat glands and cutaneous blood vessels of the overlying skin. When the patient eats (triggering salivary parasympathetic discharge), the misdirected fibres stimulate sweating and flushing instead | Occurs in 30–60% of patients (clinically significant in ~10%). Diagnosed by Minor's starch-iodine test (paint iodine on skin → dust with starch powder → give the patient food → sweating areas turn blue-black). Treatment: topical antiperspirant (aluminium chloride), botulinum toxin A injection (blocks acetylcholine release at the aberrant nerve terminals — lasts 6–12 months), interposition barrier graft (AlloDerm, SCM flap, or SMAS flap) at time of initial surgery to prevent aberrant reinnervation |
| Hypertrophic scar / keloid [23] | Abnormal wound healing with excessive collagen deposition | The modified Blair incision is placed in natural skin creases to minimise visible scarring, but some patients (especially those prone to keloid — more common in Chinese/Asian populations) develop problematic scars. Managed with silicone sheets, intralesional steroid injection (triamcinolone), or revision |
| Sunken parotid area, cosmetic problem [23] | Removal of the parotid gland leaves a volume deficit in the preauricular region → visible concavity/asymmetry | Can be addressed with SMAS flap advancement, free fat grafting, or AlloDerm implantation at the time of surgery or secondarily. This is particularly noticeable in thin patients |
Complication: sialadenitis from ductal stone — pus expressed from ductal orifice [24]
| Complication | Mechanism |
|---|---|
| Superimposed infection (sialadenitis) | Ductal obstruction by stone → salivary stasis → retrograde bacterial infection → suppurative sialadenitis. This is essentially how sialolithiasis causes parotitis [24] |
| Abscess formation | Progressive infection with walled-off pus collection → potentially compromises the airway if large or in the submandibular/parapharyngeal region [2] |
| Ductal stricture | Chronic inflammation and scarring of the duct wall → permanent narrowing → predisposes to recurrent stasis and infection even after stone removal |
| Gland atrophy | Complete chronic obstruction → the gland ceases saliva production → progressive fibrosis and atrophy. The gland eventually feels firm and non-tender, and the patient becomes asymptomatic (the gland essentially "burns out") |
| Ranula | Iatrogenic complication of transoral stone removal — excessive trauma to the sublingual gland or Wharton's duct during surgery can cause a retention cyst (ranula) in the floor of the mouth [2] |
High Yield Summary
- Five key complications of parotitis (the disease): airway obstruction, facial nerve palsy, septicaemia, parapharyngeal abscess (→ Lemierre's syndrome), osteomyelitis of adjacent bone [2]
- Airway obstruction is the most immediately life-threatening — always secure the airway first in deep neck infections
- Facial nerve palsy in parotitis = compression/neuritis from inflammation/abscess; usually reversible if treated early. Facial nerve palsy with a parotid mass = think malignancy
- Parapharyngeal abscess can lead to Lemierre's syndrome (septic IJV thrombophlebitis → septic pulmonary emboli) or descending necrotising mediastinitis
- Parotidectomy early complications: bleeding/haematoma, facial nerve palsy (transient ~5%, permanent ~1%), wound infection, salivary fistula [22]
- Parotidectomy late complications: recurrence, Frey's syndrome (gustatory sweating), hypertrophic scar/keloid, sunken parotid area [23]
- Frey's syndrome = aberrant parasympathetic reinnervation of sweat glands after auriculotemporal nerve injury → sweating and flushing during eating. Diagnosed by Minor's starch-iodine test. Treated with botulinum toxin A or barrier graft
- Mumps complications: orchitis (15–30% post-pubertal males), meningitis, pancreatitis, sensorineural deafness, encephalitis
- Distinguish mumps pancreatitis from parotitis: both raise amylase, but lipase is elevated only in pancreatitis
Active Recall - Complications of Parotitis
References
[2] Senior notes: felixlai.md, sections 322–323 [11] Senior notes: felixlai.md, section 338 [21] Lecture slides: GC 219. Infections and tumours in pharynx and oral cavity.pdf, p22 [22] Lecture slides: GC 217. Facial nerve palsy and salivary gland diseases.pdf, p79 [23] Lecture slides: GC 217. Facial nerve palsy and salivary gland diseases.pdf, p80 [24] Lecture slides: GC 219. Infections and tumours in pharynx and oral cavity.pdf, p28
High Yield Summary
- Acute suppurative parotitis = dehydrated/debilitated/post-op patient + unilateral tender parotid swelling + pus from Stensen's duct + S. aureus most common organism
- Viral parotitis = mumps (commonest viral cause) + bilateral + prodrome + no pus from duct + self-limiting 5–10 days + diagnose clinically + serology
- Pathophysiology = reduced salivary flow → stasis → retrograde bacterial seeding up Stensen's duct → suppurative infection → ± abscess
- Risk factors = dehydration, post-op, elderly, anticholinergics, duct obstruction, poor oral hygiene, immunosuppression
- Bilateral painless parotid enlargement differential: bulimia, alcoholic cirrhosis, DM, hypothyroidism, drugs (phenytoin), Sjögren's, HIV, sarcoidosis, pseudoparotomegaly (masseter hypertrophy)
- Key clinical sign = express pus from Stensen's duct orifice (opposite upper 2nd molar) by massaging the gland
- Serum amylase elevated in parotitis (parotid is the main source of salivary amylase)
- Facial nerve runs through the gland → facial nerve palsy is a complication of parotitis/abscess/surgery
- Stensen's duct = 4–7 cm long, opens opposite upper 2nd molar
- Complications: airway obstruction, facial nerve palsy, septicaemia, parapharyngeal abscess (→ Lemierre's syndrome), osteomyelitis of adjacent bone
High Yield Summary
- First question: Is it really a parotid swelling? — rule out masseter hypertrophy, cervical LNs, lipoma, vascular malformation, branchial cleft cyst
- History discriminators: Acute onset + fever + pus → infection. Meal-related intermittent swelling → sialolithiasis. Persistent progressive painless mass → neoplasm. Bilateral painless → systemic/autoimmune/metabolic
- Palpate the ducts for stones and express pus — the most important bedside manoeuvre
- Bilateral parotid enlargement DDx: pseudoparotomegaly (masseter hypertrophy), bulimia, alcoholic cirrhosis, DM, hypothyroidism, drugs (phenytoin), Sjögren's, sarcoidosis, HIV
- Facial nerve palsy + parotid mass = malignancy until proven otherwise — benign tumours do not cause CN VII palsy
- Neoplasm DDx: primary benign (pleomorphic adenoma, Warthin), primary malignant (mucoepidermoid, adenoid cystic), metastatic (from scalp/face SCC or melanoma), lymphoma
- Chronic sialadenitis: mild pain, worsens after meal, recurrent swelling — can be caused by Sjögren's or sialolithiasis
High Yield Summary
- Diagnosis of acute suppurative parotitis is clinical: sick patient + unilateral tender parotid swelling + pus from Stensen's duct + elevated amylase (with normal lipase)
- Ultrasound is the first-line investigation for any salivary gland pathology — confirms origin, detects stones, dilated ducts, lymph nodes, and can guide FNA
- FNA of the swollen parotid gland extra-orally is the best method to identify causative organisms in suppurative parotitis
- Elevated serum amylase in the absence of pancreatitis supports parotid involvement — check lipase to exclude pancreatitis
- CT with contrast is indicated when abscess is suspected (no improvement after 48 hours of IV antibiotics) or to assess deep lobe/parapharyngeal extension
- MRI is the gold standard for parotid tumour assessment (facial nerve relationship, perineural spread)
- Viral parotitis is diagnosed by clinical presentation and serology — no pus from duct, often bilateral, self-limiting
- Culture from oral cavity should be interpreted with caution — contamination by oral flora is inevitable; duct-expressed pus or FNA aspirate is more reliable
- Never do an open incisional biopsy of a parotid mass — use FNA or core biopsy, then proceed to formal parotidectomy if needed
- For chronic/bilateral parotid enlargement, investigate for Sjögren's (SSA/SSB, lip biopsy), sarcoidosis (ACE, CXR), DM, hypothyroidism, HIV, IgG4-RD, and drug history
High Yield Summary
- Acute suppurative parotitis: Rehydration + IV antibiotics [1]. Duration 10–14 days [2]. Immunocompetent: anti-staphylococcal + anaerobic cover. Immunocompromised: MRSA cover + broad Gram-negative/anaerobic cover
- I&D is indicated when no clinical response after 48 hours of IV antibiotics [2] — always get CT first to confirm abscess
- Viral parotitis (mumps): supportive only — bed rest, hydration, analgesia. Self-limiting 5–10 days. No antiviral needed. Notifiable disease
- Sialolithiasis: stepwise — conservative (small stones pass) → transoral removal → sialendoscopy → gland excision [19] if proximal/recurrent/multiple stones
- Chronic sialadenitis: hydration, sialogogues, massage, heat, antibiotics during acute attacks, remove stones, gland excision if recurrent [18]
- Deep neck abscess: secure airway → surgical drainage → IV antibiotics [21]
- Prevention of post-operative parotitis: adequate perioperative hydration + oral hygiene — this is the single most effective preventive strategy
- Key contraindications: no sialography in acute infection; no aspirin in children with viral illness; avoid ampicillin in EBV
- Frey syndrome: gustatory sweating post-parotidectomy due to aberrant parasympathetic reinnervation of skin sweat glands
High Yield Summary
- Five key complications of parotitis (the disease): airway obstruction, facial nerve palsy, septicaemia, parapharyngeal abscess (→ Lemierre's syndrome), osteomyelitis of adjacent bone [2]
- Airway obstruction is the most immediately life-threatening — always secure the airway first in deep neck infections
- Facial nerve palsy in parotitis = compression/neuritis from inflammation/abscess; usually reversible if treated early. Facial nerve palsy with a parotid mass = think malignancy
- Parapharyngeal abscess can lead to Lemierre's syndrome (septic IJV thrombophlebitis → septic pulmonary emboli) or descending necrotising mediastinitis
- Parotidectomy early complications: bleeding/haematoma, facial nerve palsy (transient ~5%, permanent ~1%), wound infection, salivary fistula [22]
- Parotidectomy late complications: recurrence, Frey's syndrome (gustatory sweating), hypertrophic scar/keloid, sunken parotid area [23]
- Frey's syndrome = aberrant parasympathetic reinnervation of sweat glands after auriculotemporal nerve injury → sweating and flushing during eating. Diagnosed by Minor's starch-iodine test. Treated with botulinum toxin A or barrier graft
- Mumps complications: orchitis (15–30% post-pubertal males), meningitis, pancreatitis, sensorineural deafness, encephalitis
- Distinguish mumps pancreatitis from parotitis: both raise amylase, but lipase is elevated only in pancreatitis
Oropharyngeal Carcinoma
Oropharyngeal carcinoma is a malignant neoplasm arising from the mucosal epithelium of the oropharynx, including the base of tongue, tonsils, soft palate, and posterior pharyngeal wall, frequently associated with HPV infection or tobacco and alcohol use.
Salivary Gland Tumours
Salivary gland tumours are a diverse group of benign and malignant neoplasms arising from the major or minor salivary glands, with pleomorphic adenoma being the most common benign type and mucoepidermoid carcinoma the most common malignant type.