Multiple myeloma in a child.

A 12-year-old girl with the diagnosis of multiple myeloma is described. She presented with a nasopharyngeal mass which was histologically found to be a plasmacytoma. Serum immunoelectrophoresis revealed an IgA-kappa M-protein (4.9 g/dl). There were approximately 20% atypical plasma cells in a bone marrow biopsy specimen. The diagnosis was further supported by immunohistochemical demonstration of cytoplasmic monoclonal IgA-kappa in the tumor cells of both the nasopharyngeal and bone marrow biopsies. The patient was treated with chemotherapy for 1 year, at which time she became refractory to treatment, based on serum IgA levels. Five months after cessation of therapy, she continues to exhibit a significant objective response, remaining clinically well with a stable, elevated serum IgA level.