Progressively pigmented thumb nail

Case presentation

Over an eight-year period, a 60-year-old man noted progressive dark discolouration of his thumb nail with disintegration of the distal nail plate (Figure 1). Dermoscopy revealed broad bands of dark pigment within the nail bed and finer radiating pigmented streaks extending into the surrounding skin (Figure 2). There were scattered pigment dots and a patchy grey–white milky veil. Excision revealed a confluent proliferation of atypical melanocytes that were intraepidermal and associated with superficial lymphocytic inflammation and fibrosis (Figure 3).