Table 4 Causes of melanonychia compared with those of subungual bleeding

Benign racial melanonychia

Direct trauma

Laugier Hunziker

Indirect microtrauma-end on repetitive trauma

Inflammation

Haemorrhagic tendency lowering threshold for effects of trauma. eg

   • Lichen planus

   • warfarin

   • Chronic paronychia

   • leukaemic

   • Trauma/friction

   • thrombocytopaenia

   • radiation

Medication e.g.

Subungual tumour

   • Minocycline

   • squamous cell carcinoma

   • Chemotherapy

   • wart

   • HIV disease or medication

   • exostosis

   • melanoma

   • pyogenic granuloma

Addison's disease

Peutz Jeghers

Subungual naevus

Benign melanocyte activation

Melanoma

Bowen's disease (in situ squamous cell carcinoma)

Onychomycosis