Bang Soon Kim

Pigmented nail with atypical melanocytic hyperplasia.

We report two cases showing black discoloration of the thumb nail which were histologically found to be acral ientiginous melanoma (ALM) in situ. A pigmented subungual lesion is more frequently malignant than benign and it is generally believed that diagnosis of subungual melanoma during the radial‐growth phase is very difficult. Our cases are particularly interesting because atypical melanocytic hyperplasia was confined to the epidermis despite the lesion being present for a long time.