Lichen planus pemphigoides evolving into pemphigoid nodularis.

Lichen planus pemphigoides (LPP) and pemphigoid nodularis are rare clinical variants of bullous pemphigoid (BP), which are characterized by histological findings of lichen planus (LP) and nodular prurigo, respectively, and the finding of linear deposits of IgG and/or C3 at the basement membrane zone in perilesional skin. In both cases bullae may arise at the site of pre-existing LP-like or nodular prurigo-like eruptions, and clinically uninvolved skin. The disease spectrum of LPP and pemphigoid nodularis differs from that of classical BP phenotype, and their presentations are often indolent. LPP may predominantly affect a younger age group and is responsive to standard treatments used in acquired autoimmune bullous diseases, while pemphigoid nodularis is more common in elderly women and is relatively resistant to therapy. We describe a patient who had LPP for nearly two decades and subsequently developed a nodular eruption with a concurrently detected antibullous pemphigoid antigen 2 (BP180) autoantibody. His overall clinicopathological features were indicative of LPP evolving into another BP variant, pemphigoid nodularis.