Lichen planus pigmentosus: A retrospective clinico-epidemiologic study with emphasis on the atypical variants

Abstract

Background: Lichen planus pigmentosus (LPP) is a relatively common pigmentary dermatosis which commonly presents as brownish or slate grey patches in diffuse, reticular and blotchy pattern. Recently, linear, flexural, and zosteriform LPP have been described. Methods: The present study was aimed to study the epidemiologic profile of LPP with a special focus on the atypical variants. In this retrospective study, case records of patients diagnosed clinically and/or histopathologically as LPP during the time period from January 2009 to December 2013 were analyzed. Results: Case records of 76 patients were analyzed. The mean age and mean duration of disease were 37.6 years and 3.5 years, respectively, with M:F = 1:2.5. The diffuse pattern of LPP was the most common in 38 (50%) patients followed by reticular in 15 (19.7%), blotchy in 12 (15.7%), and perifollicular in 3 (3.9%) patients. Five (6.6) temporally correlated the onset of LPP with the cosmetic use. The atypical variants included segmental LPP in 3 (3.9%) patients, linear LPP in 3 (3.9%), and flexural in 2 (2.6%) patients. Among three patients with segmental LPP, one had bilateral LPP over breast, one had unilateral segmental LPP, and third had co-localization of segmental LPP and vitiligo. Histopathologic changes included focal basal cell degeneration with sparse upper dermal interface dermatitis along with melanophages in the upper dermis. All patients were treated with mid-potent topical corticosteroids and/or topical calcineurin inhibitors with poor response to therapy. Conclusions: The atypical and localized variants of LPP are not uncommon and like classic LPP respond poorly to treatment.