A pigmented lesion on the finger.

A 42-year-old male, phototype III-IV, presented with an 8-month history of gradually enlarging pigmentation on the second finger of his left hand. He had no personal or familial history of skin cancer. No cryotherapy or other procedure was performed in this location. Naked-eye examination revealed an irregular hyperpigmented plaque extending from proximal to lateral nail fold, which appeared irregularly shaped and with fuzzy borders (Figure 1a). Dermoscopy showed a brown-colored area displaying parallel pattern with pigment both in furrows and ridges and a white structureless area in the proximal nail fold; in the distal part of the lateral nail fold and in the hyponychia, a slightly verrucous area with irregular light brown pigmentation was noted (Figure 1b). Irregular pigmentation of acrosyringia was also observed. Two punch biopsies were taken from the proximal and distal areas of the lesion. Histopathology reported acanthosis, hyperkeratosis and full thickness atypia of epidermal keratinocytes, and melanin in the lower epidermis (Figure 2).