Fig. 2.

Melanocytic activation. a A 49-year-old female patient with a 1.5-year history of longitudinal melanonychia located on her left hand thumbnail. Tangential matrix biopsy showed functional melanonychia. b H&E stain showed some barely recognizable melanocytes and very little pigment and localized melanophages in the dermis. H&E, ×4. c Cytologically, the melanocytes were normal and no mitoses were seen. H&E, ×40. d Immunohistochemistry with Melan-A demonstrated the melanocytes among basal epithelial cells; they were located suprabasally in the first cell layers from the base of the epithelium without an increase in the number of melanocytes. Melan-A, ×40.