Lichen planus pemphigoides

Lichen planus pemphigoides (LPP) is a rare autoimmune blistering disorder that combines features of two distinct skin conditions: lichen planus and bullous pemphigoid. In this condition, patients initially develop the characteristic flat-topped, violaceous (purple-red), itchy papules of lichen planus, and subsequently develop tense blisters (bullae) that arise both on existing lichen planus lesions and on previously uninvolved, normal-appearing skin. The blistering component is caused by autoantibodies directed against the BP180 (type XVII collagen) antigen located in the basement membrane zone of the skin, which is the same target seen in bullous pemphigoid. The disease primarily affects the skin but may also involve mucous membranes, including the oral cavity. Lichen planus pemphigoides predominantly affects adults and can cause significant discomfort due to intense pruritus (itching) and widespread blistering. Diagnosis is established through clinical examination, skin biopsy showing features of both lichen planus and subepidermal blistering, and immunofluorescence studies demonstrating linear deposition of IgG and C3 along the basement membrane zone. Some cases have been reported in association with certain medications or other triggers, though many cases are idiopathic. Treatment of lichen planus pemphigoides typically involves systemic immunosuppressive therapy. First-line treatments include systemic corticosteroids, often combined with steroid-sparing agents such as dapsone, azathioprine, or mycophenolate mofetil. Topical corticosteroids may be used for localized disease. In refractory cases, other immunosuppressants or combination therapies may be considered. The prognosis is generally favorable with appropriate treatment, and the condition may eventually remit, though relapses can occur.

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