Lichen planus pigmentosus presenting in zosteriform pattern

Lichen planus pigmentosus (LPP) has thus far been described as a condition of unknown etiology which clinically differs from the classical lichen planus (LP) by exhibiting dark brown macules and/or papules mostly in exposed areas and flexural folds and a longer clinical course without pruritus or scalp, nail or mucosal involvement. Histopathologically, LPP shows the typical changes seen in LP, but with thinning of epidermis. We report a case of LPP that developed in a unilateral, zosteriform pattern on the left flank of a 49-year-old man. This case seems to lie in the middle of the spectrum between classical LP and ashy dermatosis, and, to the best of our knowledge, is the first report of LPP presenting in the zosteriform pattern.