Linear IgA bullous dermatosis. An immunologically defined disease.

Linear IgA bullous dermatosis (LABD) can mimic bullous pemphigoid (BP) and/or dermatitis herpetiformis (DH) both clinically and histologically. LABD, however, can be distinguished from BP and DH by direct immunofluorescent (IF) demonstration of linear IgA deposits along the basement membrane zone. A retrospective study of 234 cases of BP, 27 cases of LABD, 60 cases of DH, and 20 cases of cicatricial pemphigoid (CP) revealed that BP patients are significantly older than LABD or DH patients and LABD patients are significantly older than DH patients. BP and CP occur more frequently in women (65-70%) than LABD or DH (44-48%). The frequencies of C3 deposits in the basement membrane zone (BMZ) are significantly higher in BP (85%) compared with LABD (18.5%) and DH (28.3%). LABD patients varied in their response to various therapeutic agents. Some responded to corticosteroids and some to sulfones alone, whereas others required a combination of corticosteroids and sulfones.