Abnormal Nails
Differential Diagnosis
Common Diagnoses
- Psoriasis
- Fungal Infection: Onychomycosis
- Trauma to Nail Bed
- Trauma Due to Biting (Also Hang Nail)
- Onychogryphosis (OG)
Occasional Diagnoses
- Trophic Changes (Beau’s Lines): Appear 2–3 Months after Severe Illness
- Hand Eczema
- Longitudinal Ridging (Onychorrhexis)
- Chronic Paronychia
- Clubbing (Various Causes)
- Autoimmune Disease (e.g. Alopecia Areata, Lichen Planus)
- Koilonychia (Spoon Nails): Iron Deficiency Anaemia and Plummer–Vinson Syndrome
Rare Diagnoses
- Subungual Melanoma
- Leuconychia (e.g. Liver Disease, Diabetes)
- Lamellar Nail Dystrophy
- Yellow Nail Syndrome (May be Accompanied by Chronic Bronchitis, Bronchiectasis or Pleural Effusion)
- Exfoliative Dermatitis: Nail Shedding
- Nail Dystrophy Due to Poor Circulation (e.g. Raynaud’s Disease)
- Epidermolysis Bullosa
Ready Reckoner
Key distinguishing features of the most common diagnoses
| Trauma | Psoriasis | Fungal | Biting | OG | |
|---|---|---|---|---|---|
| Pitting on Nails | No | Yes | No | No | No |
| Nails Symmetrically Affected | No | Yes | No | Possible | No |
| Ragged Edges | No | No | No | Yes | No |
| Increased Thickness | Possible | Possible | Yes | No | Yes |
| Friable and Crumbly | No | Possible | Yes | No | No |
Possible Investigations
Likely:Nail clippings for mycology.
Possible:Urinalysis, FBC.
Small Print:LFT, CXR.
- Nail clippings for mycology may be the only way to differentiate psoriatic nail dystrophy and onychomycosis.
- Urinalysis worthwhile if nails are unusually white: This can occur in diabetes.
- FBC may confirm iron deficiency anaemia in koilonychia.
- LFT: To assess liver function in leuconychia.
- CXR worthwhile if chest symptoms with clubbing or yellow nails.
Top Tips
- Don’t confine your examination to the nails – useful clues may be found elsewhere, e.g. patches of psoriasis or coexisting tinea corporis.
- The commonest differentials are psoriasis and fungal infections. The latter are usually asymmetrical.
- Patients usually worry about vitamin or calcium deficiencies – these are never the real cause.
- By the time Beau’s lines are obvious to the patient, 3 months or so will have passed from the precipitating event – look back in the records for aetiological clues.
Red Flags
- Subungual melanoma is rare and is easily confused with the much more common subungual haematoma. Possible pointers include nail destruction, extension of pigment onto the nail fold and longitudinal bands of pigment. If in doubt, refer.
- Clubbing is really an abnormality of the fingertips; if noted, be alert to signs of major pulmonary or cardiac disease. Carcinoma of the lung is the commonest cause.
- Don’t assume crumbly white nails are caused by fungus. Before embarking on lengthy antifungal treatment, try to confirm the diagnosis with nail clippings.
- Severely bitten nails may be a minor symptom of a major anxiety disorder. Be aware of the possible need to explore psychological issues.