Family medicine
Nail Abnormalities
Nail abnormalities are changes in the color, shape, texture, or growth of the fingernails or toenails that may indicate local disease, systemic conditions, or nutritional deficiencies.
Murtagh Diagnostic Strategy
| Category | Diagnosis | Key Discriminator | Cantonese Question / Finding |
|---|---|---|---|
| Probability Diagnosis | Onychomycosis (tinea unguium) | Yellow-white discolouration, thickened, crumbly nail; usually toenails; KOH +ve | 「隻甲有冇變黃、變厚、易碎？」 |
| Nail psoriasis | Pitting, oil-drop sign, onycholysis, subungual hyperkeratosis; associated skin plaques [1][2] | 「隻甲面有冇好多細細嘅窿（凹坑）？身體有冇紅色皮屑嘅疹？」 | |
| Traumatic nail dystrophy | Clear history of trauma or repetitive micro-trauma (e.g., tight shoes, sports) | 「隻甲有冇撞傷過？著嘅鞋會唔會太細？」 | |
| Serious Not To Miss | Subungual melanoma | Longitudinal melanonychia with Hutchinson sign (periungual pigmentation), >3mm width, irregular borders | 「甲底有冇一條黑色嘅線？旁邊皮膚有冇變黑？」 |
| Squamous cell carcinoma (subungual) | Persistent non-healing lesion under one nail; may mimic chronic paronychia | 「有冇隻甲附近成日唔好，好耐都唔埋口？」 | |
| Systemic disease (CKD → half-and-half nails; Liver → Terry's nails; Endocarditis → splinter haemorrhages) | Associated systemic symptoms; proximal white / distal brown (half-and-half); Muehrcke's bands in hypoalbuminaemia [3] | 「有冇腎病、肝病？有冇水腫、面黃？」 | |
| Pitfalls | Lichen planus of nails | Thinning, ridging, pterygium (scarring of nail fold into nail bed); may have oral/skin LP | 「口腔入面有冇白色紋或者損口？」 |
| Chronic paronychia (Candida) | Swollen, tender nail fold; loss of cuticle; wet-work occupation | 「指甲旁邊有冇紅腫？你做嘢係咪成日濕水？」 | |
| Habit-tic deformity | Central longitudinal ridge/furrow on thumbnail from repetitive picking of proximal nail fold | 「有冇習慣性噉挖或者撳甲皮？」 | |
| Masquerades | Koilonychia | Spoon-shaped nails; associated pallor, fatigue | 「隻甲有冇凹落去好似匙羹咁？有冇易攰、面青？」 |
| Brittle/Onycholysis (Plummer's nails in hyperthyroidism) | Thyrotoxicosis symptoms: weight loss, tremor, heat intolerance | 「有冇心跳快、手震、怕熱、消瘦？」 | |
| Drug-induced nail changes | Temporal correlation with medication (chemo → Beau's lines/melanonychia) | 「最近有冇開始食新嘅藥或者做化療？」 | |
| Trying to Tell Me Something? | Cosmetic concern / anxiety / body image | No systemic disease; nail change is minor but patient very distressed | 「你覺得隻甲嘅問題對你外觀影響大唔大？有冇因為咁覺得好煩惱？」 |
| Occupational stress / fear of cancer | Triggered by seeing someone with nail melanoma, or work concern | 「點解揀咗今日嚟睇呢？係咪有啲嘢特別擔心？」 |
Nail Abnormalities — Family Medicine Clinical Test Note
| Time | Task | Cantonese Key Phrases | Why It Scores Marks |
|---|---|---|---|
| 0:00–0:30 | Greeting, rapport, open question | 「你好，我係X醫生。今日有咩可以幫到你呀？」(Hello, I'm Dr X. What can I help you with today?) | Friendly opening scores interpersonal marks; open question lets patient tell their story |
| 0:30–1:30 | HPI: onset, duration, which nails, progression, symptoms (pain/itch), associated skin/joint changes | 「你隻指甲幾時開始唔正常㗎？係邊隻手指/腳趾呀？有冇痛或者痕？有冇其他皮膚或者關節嘅問題？」 | Characterises the nail change systematically; psoriasis and fungal infection are top DDx |
| 1:30–2:30 | Red flags & targeted Hx: trauma, new medications, systemic symptoms (weight loss, fever), occupation, chemical exposure, diabetes, peripheral vascular disease | 「有冇撞傷過隻甲？最近有冇食新嘅藥？有冇糖尿病？你做咩工作㗎？平時有冇接觸化學品或者成日濕水？」 | Rules out serious causes (melanoma, systemic disease) and identifies occupation as risk factor |
| 2:30–3:30 | ICE: Ideas, Concerns, Expectations | 「你自己覺得指甲點解會變成咁呀？」(Ideas)「你最擔心啲咩呢？」(Concerns)「你今日嚟，最希望醫生幫到你啲咩？」(Expectations) | ICE is heavily weighted in the Case Report; uncover hidden agenda |
| 3:30–4:30 | PMH, Drug Hx, Allergy, FH, Social Hx (smoking, alcohol, occupation, stress) | 「你平時有冇長期病患？有冇食開啲咩藥？有冇藥物敏感？屋企人有冇皮膚病？你有冇煙酒？最近生活壓力大唔大？」 | Completes the case report; family history of psoriasis or autoimmune disease is key |
| 4:30–5:15 | Signpost → brief physical exam / describe what you would examine | 「我想睇吓你隻指甲同埋皮膚，可以俾我睇吓嗎？」(Permission) | Permission-seeking scores marks; physical exam anchors the most likely diagnosis |
| 5:15–6:00 | Summarise, safety-net, close | 「等我總結一下…你隻指甲變咗(描述)，已經有X個月，冇痛…我會幫你安排(檢查/轉介)。如果指甲突然變黑或者有痛，要即刻返嚟睇。仲有冇其他嘢想問？」 | Summarise checks understanding; safety-net for melanoma/infection is essential |
Uncovering the hidden agenda: The patient may present with "ugly nails" but actually be worried about fungal spread to family, nail melanoma, or an underlying systemic disease (e.g., psoriasis affecting work/self-esteem). Always ask: 「點解揀咗今日嚟睇呢？」(Why did you decide to come today?)
| Domain | English Question | Cantonese Question | Why It Matters | If Positive, Think Of |
|---|---|---|---|---|
| Onset & Duration | When did you first notice the nail change? | 「你幾時開始發覺隻甲有問題？」 | Acute vs chronic narrows DDx | Acute → trauma, paronychia; Chronic → fungal, psoriasis |
| Which nails | Which fingers/toes? One or many? | 「係邊隻手指/腳趾？一隻定幾隻？」 | Distribution pattern is diagnostic | Single nail → trauma, melanoma; Multiple → psoriasis, fungal |
| Nail change description | What does the nail look like — colour, thickness, shape, pitting? | 「隻甲有冇變色、變厚、凹凸不平、或者甩開？」 | Identifies specific morphology | Pitting → psoriasis; Yellow/thick → onychomycosis; Dark streak → melanoma |
| Pain | Is it painful? | 「有冇痛？」 | Pain suggests infection or ingrown nail | Acute paronychia, ingrown toenail |
| Associated skin | Do you have any rashes, scaly patches, especially on elbows, knees, scalp? | 「身體其他地方有冇出疹？特別係手踭、膝頭、頭皮？」 | Nail psoriasis present in up to 50% of psoriasis patients [1] | Psoriasis |
| Joint pain | Do you have any joint pain or stiffness? | 「有冇關節痛或者僵硬？」 | Nail disease is one of the strongest clinical predictors for psoriatic arthritis [2] | Psoriatic arthritis |
| Trauma/habits | Any injury? Do you bite nails or pick at them? | 「有冇撞傷過？有冇咬甲或者挖甲嘅習慣？」 | Mechanical cause, habit-tic deformity | Trauma, habit-tic dystrophy |
| Occupation / wet work | What is your job? Do your hands get wet often? | 「你做咩工㗎？隻手係咪成日濕水？」 | Wet work → candidal paronychia, contact dermatitis | Chronic paronychia (Candida), irritant contact dermatitis |
| Medications | Are you taking any new medications? | 「最近有冇食新嘅藥？」 | Drug-induced nail changes (e.g., chemotherapy → Beau's lines, melanonychia) | Drug-induced nail dystrophy |
| PMH: Diabetes, PVD, thyroid, iron deficiency | Any chronic diseases — diabetes, thyroid, anaemia? | 「有冇糖尿病、甲狀腺問題、或者貧血？」 | Diabetes → fungal risk + poor healing; Thyroid → brittle nails; Anaemia → koilonychia | Onychomycosis, koilonychia (iron deficiency), thyroid nail changes |
| Family Hx | Anyone in the family with skin disease or nail problems? | 「屋企人有冇皮膚病或者指甲問題？」 | Psoriasis has strong genetic component | Psoriasis |
| Red flag: dark streak | Have you noticed a dark line or spot under the nail? | 「有冇見到甲底下有黑色線或者黑點？」 | Must not miss subungual melanoma | Subungual melanoma |
| Cosmetics | Do you use nail polish, gel nails, or acrylic nails? | 「有冇搽甲油、做gel甲或者水晶甲？」 | Contact allergy / chemical damage | Contact dermatitis, brittle nails |
| Functional impact | Does it affect your daily life, work, or how you feel? | 「對你日常生活、返工、或者心情有冇影響？」 | Biopsychosocial assessment | Embarrassment, occupational difficulty |
Case Report Form Answer Builder
- CC: Nail abnormality (specify: discolouration / thickening / pitting / dark streak / separation) × duration
- HPI must include: Which nails affected, onset/progression, morphology (colour, texture, shape), associated symptoms (pain, itch), precipitating factors (trauma, wet work, new meds), associated skin lesions (scalp, elbows, knees), joint symptoms, functional impact, prior treatment attempted
| Likely RFC Examples | Best Single-Answer Phrasing |
|---|---|
| Cosmetic concern about nail appearance | "Patient presents for assessment of nail discolouration / thickening causing cosmetic concern" |
| Worried about cancer (dark streak) | "Patient presents with concern about a dark line under the nail, worried it may be cancer" |
| Nail problem not responding to self-treatment | "Patient presents for persistent nail thickening despite OTC antifungal treatment" |
| Triggered by new symptom (e.g., pain, spread) | "Patient presents because nail abnormality is worsening / now painful / spreading to other nails" |
| Component | Example Wording |
|---|---|
| Ideas | "Patient thinks the nail change is due to fungal infection / aging / poor nutrition" |
| Concerns | "Patient is worried the nail change could be a sign of cancer / serious disease / contagious to family" |
| Expectations | "Patient hopes for a definitive diagnosis and effective treatment / referral to dermatologist" |
- Onychomycosis — if: older patient, toenails, yellow-white thickened crumbly nails, no skin plaques, no pitting
- Nail psoriasis — if: pitting, oil-drop sign, onycholysis, subungual hyperkeratosis, known/suspected psoriasis, joint symptoms
- Choose based on the stem: match the morphology description + associated features
- Minimum evidence: nail morphology description + one supporting feature (e.g., KOH positive, or concurrent psoriatic plaques)
| DDx | Key Discriminator |
|---|---|
| Onychomycosis (if nail psoriasis is most likely, and vice versa) | KOH/culture positive; no pitting; no skin plaques |
| Traumatic nail dystrophy | Clear trauma history; single nail; normal other nails |
| Subungual melanoma | Longitudinal melanonychia, Hutchinson sign, single digit, progressive widening |
| Domain | Problem |
|---|---|
| Biological | Nail dystrophy causing difficulty with fine motor tasks / secondary infection risk |
| Psychological | Embarrassment / anxiety about appearance or fear of serious disease (cancer) |
| Social | Occupational impact (e.g., food handler, healthcare worker unable to work with visible nail disease) / avoidance of social activities |
| Diagnosis/DDx | Best Supporting Physical Sign | How to Elicit | Why It Supports This Diagnosis |
|---|---|---|---|
| Onychomycosis | Yellow-white distal/lateral subungual hyperkeratosis with crumbly debris under nail plate | Inspect nails; gently lift distal nail edge to see subungual debris | Characteristic morphology of dermatophyte infection; confirmed by KOH scraping |
| Nail psoriasis | Nail pitting — multiple tiny pits scattered over nail plate [1][2] | Inspect nail surface under good light; count pits | Typical nail abnormality of psoriasis is pitting [2]; also look for oil-drop sign, onycholysis |
| Subungual melanoma | Hutchinson sign — pigmentation extending from nail bed to proximal/lateral nail fold skin | Inspect periungual skin for brown-black pigmentation beyond the nail plate | Pathognomonic for subungual melanoma; warrants urgent referral |
| Lichen planus | Pterygium — scarring of proximal nail fold fusing to nail bed, destroying the nail plate | Inspect for triangular scarring from cuticle growing onto nail plate | Unique to lichen planus among nail diseases |
| Iron deficiency (koilonychia) | Spoon-shaped (concave) nail plate | Place a drop of water on nail surface — it stays in the concavity | Koilonychia is classic for iron deficiency anaemia; check conjunctival pallor |
| Chronic paronychia | Swollen, erythematous, boggy proximal nail fold with loss of cuticle | Inspect and gently palpate nail fold; note absent cuticle | Chronic Candida infection of nail fold in wet-work patients |
Must-Not-Miss Red Flags
- Longitudinal melanonychia with Hutchinson sign → Urgent dermatology referral to rule out subungual melanoma. Single digit, darkening, widening stripe, pigment extending to periungual skin.
- Single nail dystrophy not responding to treatment for > 6 months → Consider SCC or amelanotic melanoma; biopsy needed.
- Splinter haemorrhages + fever + new murmur → Infective endocarditis — not just "nail abnormality."
- Half-and-half nails (Lindsay's nails) → Screen for CKD.
- Koilonychia in a child or young woman → Check iron studies.
Top traps that lose marks:
| Trap | How to Avoid |
|---|---|
| Diagnosing onychomycosis without mentioning need for KOH/culture confirmation | Always state: "would confirm with nail clipping KOH microscopy and fungal culture" |
| Missing psoriatic arthritis in a nail psoriasis case | Always ask about joint symptoms; nail disease is the strongest clinical predictor for psoriatic arthritis [2] |
| Forgetting to examine other nails + skin + scalp + joints | Systematically examine all 20 nails + extensor surfaces + scalp + DIP joints |
| Not asking about the dark streak → missing melanoma | Always ask about colour change/dark line even if patient doesn't mention it |
| Writing "fungal infection" as the sole diagnosis when pitting is described | Pitting = psoriasis, not fungal; fungal = thickened, crumbly, yellow-white |
| Forgetting ICE → losing easy marks | Use the three exact Cantonese ICE questions listed above |
Shortest safe management line for closing:
- Onychomycosis: "I will take a nail clipping for testing. If confirmed fungal, we can discuss antifungal treatment options."
- Psoriasis: "I would like to refer you to a dermatologist for further assessment and management."
- Dark streak: "This needs urgent review by a skin specialist. I'll arrange a referral as soon as possible."
- Safety-net: 「如果隻甲突然變黑、有痛、或者流膿，要即刻返嚟睇。」
High Yield Summary
What to ASK: Onset, which nails, morphology (pitting vs thickening vs dark streak), associated skin lesions (scalp/elbows/knees), joint symptoms, occupation/wet work, trauma, medications, dark streak (melanoma screen), ICE, functional impact.
What to WRITE: CC with specific nail change description + duration; RFC = the real reason they came today (often cosmetic concern or cancer fear); ICE verbatim; Most likely Dx supported by morphology; DDx including fungal vs psoriasis vs melanoma; biopsychosocial problems; one physical sign (pitting for psoriasis, subungual debris for fungal, Hutchinson sign for melanoma).
What NOT to MISS: Subungual melanoma (Hutchinson sign, single nail dark streak); psoriatic arthritis association with nail psoriasis; systemic disease signs (half-and-half nails = CKD, Terry's nails = liver disease, koilonychia = iron deficiency); always confirm onychomycosis with KOH before treating.
Active Recall - Family Medicine Clinical Test
[1] Lecture slides: Derm General Clerkship 2026 Part1.pdf (p23) — "Nail abnormalities are present up to 50% of patients with psoriasis; pitting, oil-drop sign, distal onycholysis" [2] Senior notes: MBBS Final MB (Medicine) (Felix PY Lai).pdf (p1795) — "Nail psoriasis: pitting, leukonychia, oil-drop sign, onycholysis, subungual hyperkeratosis; strongest clinical predictor for psoriatic arthritis" [3] Senior notes: Block A - Glomerular and Tubulo-interstitial Diseases and Acute Kidney Injury.pdf (p20) — "Muehrcke's bands — white bands in hypoalbuminaemia; same mechanism as leukonychia/Terry's nails in chronic liver disease"
Mouth Ulcers / Sore Tongue
Mouth ulcers are painful breaks in the oral mucosa, and a sore tongue (glossitis or glossodynia) refers to inflammation or pain of the tongue, both arising from causes such as trauma, nutritional deficiencies, infections, autoimmune conditions, or systemic diseases.
Nasal Drip (rhinorrhoea) / Nasal Congestion
Rhinorrhoea is the discharge of mucus from the nasal passages, while nasal congestion is the obstruction of airflow due to mucosal swelling and secretions, both commonly resulting from inflammation, infection, or allergic processes.