Pemphigoid nodularis associated with autoantibodies to the NC16A domain ofBP180 and a hyperproliferative integrin profile

Pemphigoid nodularis, a rare variant of bullous pemphigoid, has clinical fe atures resembling prurigo nodularis, with blisters arising from normal-appe aring or nodular skin. The fine antigenic epitope of the autoantibodies and the mechanism accounting for the nodular phenotype has not been delineated . We describe a patient with pemphigoid nodularis that fulfilled the criter ia of bullous pemphigoid by histopathologic examination and direct and indi rect immunofluorescence studies. Immunopathologic examination also revealed in situ deposition and circulating autoantibodies of all IgG subclasses, e xcept IgG3, and both light chains to the patient's skin basement membrane. By immunoblotting, the patient's IgG autoantibodies labeled BP180, BP230, a nd an unidentified 150-kd epidermal protein and mapped the BP180 epitope to the MCW-1, region 2 of the NC16A domain. The nodular plaque skin showed ex pression of alpha -6 and beta -1 integrin subunits, mediators of matrix-cel l signaling and proliferation, at the basal and the suprabasal epidermis, a pattern found in psoriasis, which is the prototype of hyperproliferative d ermatoses.