Neutrophilic, urticaria-like erythema associated with immunoglobulin A monoclonal gammopathy of undetermined significance.

A 70-year-old-male had suffered from non-pruritic, erythematous eruptions on the trunk for 3 months without any general symptoms. The individual lesions lasted for several days. Laboratory investigation showed marked elevation of serum immunoglobulin A (2235 mg/dL) with monoclonal gammopathy (IgA k-type). Monoclonal gammopathy of undetermined significance was diagnosed. Histopathological examination of the eruption revealed diffuse neutrophilic infiltration with leukocytoclasia in the dermis. There was no vasculitis. Treatment with antihistamines alone was not effective. Diaphenyl sulfone (DDS) at 75 mg/day dramatically improved the skin lesions. A similar case of urticarial erythema associated with IgA myeloma has been previously reported. We suggest that neutrophilic, urticaria-like erythema associated with IgA monoclonal gammopathy may be regarded as a new entity.