A sun-induced asymmetrical dark lesion

Case presentation

Over a 12-month period, a 73-year-old woman noted progressive growth and darkening of a 0.9 x 1.2 cm lesion on the dorsal aspect of her left hand (Figure 1). The surrounding skin was mottled and sun damaged. Dermoscopy revealed an asymmetrical, dark tan to black lesion with an irregular scalloped border (Figure 2). There were rippled broad bands of pigment that were confluent in areas, but there was no well developed pigment network. Pale dots interrupted the pigmentary pattern. Skin biopsy showed an epidermis with a thick horny layer and basal keratinocytes with pigment but no melanocytic proliferation (Figure 3).