Lichen planus pemphigoides (LPP) is a very rare, acquired, autoimmune blistering disorder with characteristics of both lichen planus (LP) and bullous pemphigoid (BP). The condition typically presents in the fifth decade of life with a slight female predominance. However, it is not uncommon to present in children, and in such cases, there is a male predominance.

LPP is usually idiopathic but has been associated with several medications, most commonly angiotensin-converting enzyme (ACE) inhibitors. Other implicated agents include Chinese herbs, cinnarizine, interferons, narrowband UVB, psoralen plus UVA (PUVA), ribavirin, simvastatin, and weight-reduction products.

Initially, patients present with lesions characteristic of LP: pink-to-violaceous, flat-topped, pruritic, polygonal papules and plaques that localize most commonly to flexural surfaces but may be widespread. Within months, tense vesicles and bullae develop on the LP lesions as well as on uninvolved skin, usually in an acral distribution. Concomitant onset of both conditions has also been described. Oral mucosal involvement is not uncommon.

The pathogenesis of LPP is not completely understood. However, it is thought that injury to basal keratinocytes exposes basement membrane and hemidesmosome antigens, such as BP180 and BP230, leading to autoantibody formation.