Lichen planus pemphigoides: a clinicopathological study of nine cases.

Lichen planus pemphigoides is a rare condition characterized by blisters arising on normal or erythematous skin in a patient with concurrent lichen planus. It must be distinguished from bullous lichen planus, in which, as a consequence of severe basal cell hydropic degeneration, blisters arise within lichenoid papules or plaques. We present a clinicopathological study of nine cases of lichen planus pemphigoides, and report histological, immunofluorescent, ultrastructural and immuno-electronmicroscopical observations. We distinguish lichen planus pemphigoides from bullous lichen planus and consider the differential diagnosis. We propose that lichen planus pemphigoides does not represent a homogeneous condition: it may represent a number of bullous dermatoses that develop as a consequence of exposure of different basement membrane antigens following severe damage to the epidermal basement membrane as part of the lichenoid inflammatory process.