A case of mixed bullous disease of epidermolysis bullosa acquisita and linear IgA bullous dermatosis.

A 75-year-old Japanese male visited us with bullous eruptions on the extremities. Physical examination revealed large bullae on the hands, lower legs and feet. The oral mucosa was also involved. Histology disclosed subepidermal blister with inflammatory cell infiltrates in the dermis. Direct immunofluorescence showed deposits of IgG and IgA at the cutaneous basement membrane zone. Indirect immunofluorescence on 1 M NaCl-split human skin sections demonstrated that the patient's IgG antibodies reacted with the dermal side of the split, while IgA antibodies reacted with the epidermal side. Immunoblotting showed that the patient's serum reacted with the NC1 domain of type VII collagen (290-kDa epidermolysis bullosa acquisita antigen) as well as the 120-kDa linear IgA bullous dermatosis antigen, LAD-1. Systemic prednisolone resulted in a favorable response. From the clinicopathological findings, the present case is not consistent with either epidermolysis bullosa acquisita or IgA bullous dermatosis. Therefore, we regarded the case as mixed bullous disease of epidermolysis bullosa acquisita and linear IgA bullous dermatosis. Such a case has not been previously reported.