Atypical malignant melanoma of the nail apparatus

Malignant melanoma of the nail is a serious disease with a five year survival rate of between 21% (Booher & Pack, 1957) and 50% (Graham, 1973). The diagnosis of atypical cases ultimately depends on interpreting histological material. We report here a case in which two initial biopsies of the affected nail failed to show malignant melanoma. The diagnosis was eventually made by formal longitudinal nail biopsy including matrix tissue proximal to the dystrophic area, and examination of sections cut at several levels.