Lichen planus pigmentosus-inversus in adolescence

Lichen planus pigmentosus (LPP) is an uncommon variant of lichen planus, which manifests as hyperpigmented dark brown macular hyperpigmentations chiefly involving the face and upper extremities. The histopathologic changes consist of vacuolar degeneration of the basal layer, presence of dermal melanophages, and lichenoid lymphocytic infiltrations. LPP with exclusive localization in intertriginous areas is named as LPP-inversus, and is infrequently reported in previous dermatologie literature. A 16-year-old girl presented wim several brownish to dark grayish patches on bom axilla for 7 months. The lesions were asymptomatic and did not have preceding erythema. The patient had not come into contact with any chemicals and denied existence of previous allergy episodes, and her medical history was non-contributory. A skin biopsy from a brownish patch revealed vacuolar alteration of the basal layer, and band-like lymphocytic infiltration with pigment incontinence. We report a typical case of LPP-inversus with relevant literature.