[Pruritus-strong predictor of treatment response in lichen planus pigmentosus inversus]

Lichen planus pigmentosus inversus (LIPPI) is a rare variant of lichen planus, predominantly affecting intertriginous skin areas. Existing knowledge is mostly based on case reports, with few systematic reviews available. A systematic literature search identified 105 cases from case reports and series. Extracted data included demographics, clinical features, comorbidities, treatments, and outcomes. Statistical analysis included descriptive methods and uni-/multivariate logistic regression. The cohort was 64.8% female, with a median age of 58 years. Most lesions affected multiple inverse areas (55.2%). Pruritus was reported only in 44.8% of patients. Median time to diagnosis was 6 months. Treatment response was observed in 47.6% of cases, mostly with topical corticosteroids or calcineurin inhibitors. Pruritus proved to be a strong predictor of treatment response (odds ratio [OR] 4.17), as did, to a lesser extent, shorter disease duration until diagnosis (OR 0.93 per month). Ethnicity and comorbidities had no significant effect in multivariate analysis. LIPPI presents with considerable clinical and demographic variability. Pruritus and early diagnosis may be associated with better treatment outcomes and could serve as relevant prognostic indicators.