Acquired bullous dermatosis associated with IgA multiple myeloma: a case report.

We present the case of a patient with IgA paraprotein who developed hemorrhagic subepidermal vesicles and bullae with numerous neutrophils. Direct immunofluorescence test (DIF) showed weak deposits of IgA lambda paraprotein at the dermal-epidermal junction and at the intercellular level in the basal layer of the epidermis, and stronger deposits in a perivascular and diffuse pattern in the dermis. Indirect immunofluorescence (IIF) test revealed the presence of circulating IgA lambda antibodies reacting with the intercellular space of monkey and guinea pig esophagus and human skin. A blood test revealed an IgA lambda paraprotein and multiple myeloma stage I(0) was diagnosed in a later hematological study. Dapsone was prescribed and cutaneous lesions improved. This is the second report of subepidermal vesicles and bullae with dermal deposits of IgA paraprotein appearing prior to diagnosis of an IgA multiple myeloma, and it is a unique case with circulating IgA lambda antibodies reacting with the intercellular space of epithelia.