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Probability diagnosis

Fungal infection: onychomycosis


  • trauma to nail bed

  • trauma from biting

  • trauma from habit picking




Serious disorders not to be missed


Iron deficiency: koilonychia

Liver disease: leuconychia

Endocarditis: splinter haemorrhages

Chronic kidney failure: white bands, half-and-half nail

Glomus tumour

Bowen disorder/squamous cell carcinoma

Pitfalls (often missed)

Atopic dermatitis (pitted nails)

Lichen planus

Pyogenic granuloma (usually with ingrowing toenails)

Drug effects (e.g. tetracycline)

Pseudomonas infection

Connective tissue disorders (e.g. SLE)

Arsenic (Mees stripes)

Is the patient trying to tell me something?

Consider onychotillomania, where patients pick and self-mutilate their nails, resulting in parallel transverse grooves (washboard deformity or habit-tic nails).

Key history

Enquire about a history of severe stress or illness and possible onychotillomania, be it excessive nail biting, picking or cleaning. Ask whether the hands are frequently in wet work (e.g. dishwashing, soaps and detergents) or dirt.

Key examination

Careful examination of nails: look for associated skin disease (e.g. psoriasis, atopic dermatitis, tinea pedis, lichen planus)

Key investigations

  • Nail clippings for culture and histology

  • FBE and ESR

  • Consider LFTs and CXR

Diagnostic tips

  • Clubbing is an abnormality of the fingertips rather than nails.

  • Crumbly white nails are not always caused by fungus.

  • Skin disorders that can involve nails include atopic dermatitis, psoriasis, epidermolysis bullosa, exfoliative dermatitis and lichen planus.

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