Unilateral ashy dermatosis

We report a 79-year-old woman with ashy dermatosis having unilateral distribution. Asymptomatic brownish or ash-colored pigmented macules had appeared on the left side of her chest two years prior to her first visit to our department. The eruption gradually spread over the left side of the face and the anterior aspects of the left trunk and waist. Histopathologic features of the lesions were a lichenoid tissue reaction including vacuolation of basal cells with mononuclear cell exocytosis, Civatte bodies in the lower epidermis, mild perivascular lymphocytic infiltration, and dermal melanosis. We diagnosed this case as a variant of ashy dermatosis, or "unilateral ashy dermatosis" as previously described. We discussed the histological differences between ashy dermatosis and lichen planus pigmentosus.