Lichen planus pemphigoides: Identification of three distinct histopathological patterns

ABSTRACT Background: Lichen planus pemphigoides (LPP) is a rare autoimmune blistering skin disease and with sporadic case reports. Aim: This study aims to describe the clinical and histopathological features of LPP. Materials and Methods: Histopathology reports signed out as LPP were retrieved over 10 years. A review of their histopathology slides and immunofluorescence (IF) findings was done. Results: There were 14 cases in total. The male: female ratio was 1.3:1. The mean age was 53 years (range: 5–80). Involvement of the entire body was seen in 4 cases (28.57%) and limbs alone in 5 cases (35.7%). There was no mucosal involvement. Three patients had associated lichen planus (LP) (21%). We were able to segregate the cases into three distinct histopathologic patterns: bullous pemphigoid (BP)-like, bullous LP-like and erythema multiforme-like. Both direct IF (DIF) and indirect IF (IIF) were done. 12/13 cases were DIF positive (92%). IIF was positive for BP 180 and BP 230 in 5 (35.7%) and 1 (7.14%) cases. Conclusion: This is the largest case series of LPP. The heterogeneity of histopathologic patterns underscores the need for DIF/IIF for timely and accurate diagnosis.