Unilateral lichen planus pigmentosus mimicking acral lentiginous melanoma

The authors report a case of a Latin American woman who developed progressive pigmentation primarily involving two digits of her right hand. She was scheduled for amputation based on a presumptive histologic diagnosis of melanoma with regression. Dermatology consultation with repeat biopsies disclosed a lichenoid tissue reaction with marked pigment incontinence and no evidence of melanoma. This report should prompt physicians to include lichen planus pigmentosus in the differential diagnosis of acral lentiginous melanoma.