Dermatomyositis associated with primary intramuscular B cell lymphoma.

A rare case of dermatomyositis associated with primary intramuscular malignant lymphoma is described. A 40-year-old Japanese woman noticed swelling of the right thigh during the treatment of dermatomyositis with prednisolone, azathioprine and cyclophosphamide. A biopsy specimen taken from the right quadriceps muscle revealed infiltration of lymphoma cells which were positive for CD20. We reviewed 12 cases of dermatomyositis associated with malignant lymphoma reported in Japanese literature between 1984 and 1996.