Lichen planus pigmentosus inversus: case report and systematic review.

Lichen planus pigmentosus inversus (LPPI) is a rare variant of lichen planus characterized by well-demarcated, often slight pruritic, dark-gray plaques in intertriginous zones, hence the attribute of "inversus". It was originally described by Pock et al. in 2001, and less than 100 cases have been reported to date. Here, we present a case of a 52-year-old male with a two-month duration of gray-brownish plaques in bilateral axillary, submammary, antecubital, and inguinal folds. No triggering agent was present, and the biopsy showed an interface/lichenoid dermatitis with plenty of pigment incontinence. Topical tacrolimus 0.1% ointment was administered with moderate improvement at five weeks. A review of the literature showed no significant differences in involved sites and age distribution among genders, with a slightly longer duration of manifestations in females. The most administered therapeutic agents were topical corticosteroids, alone or in combination with other agents, and tacrolimus.