Biclonal gammopathy in multiple myeloma: a case report.

Monoclonal gammopathy is a group of B-cell disorders which result in the production of a specific and unique monoclonal immunoglobulin (M-component). Biclonal gammopathy is characterized by the simultaneous appearance of two different M-components. The incidence is about 1% of all monoclonal gammopathy. This paper reports on a 48-year-old male who had a chief complaint of back-pain beginning 7 months earlier. A physical examination was unremarkable, except for anemia and tenderness in the back. Hemoglobin was 5.4 g/dl, white blood cells 4.5 x 10(3)/microliter, platelets 157 x 10(3)/microliter, and reticulocytes 0.9%. Serum iron was 79 mg/dl, and total iron-binding capacity was 210 mg/dl. A blood smear showed the formation of rouleaux, but no plasma cells were found. Serum creatinine was 5.4 mg/dl, with a creatinine clearance of 18.1 ml/min. Serum electrolytes were normal except for serum calcium which was 14.4 mg/dl. The urinalysis showed strongly positive proteinuria (+2), with negative Bence Jones protein. Serum protein electrophoresis showed an increase and a spike pattern of beta-2 globulin (2.8 g/dl) and alpha-2 globulin (1.5 g/dl), with normal gamma globulin. By nephelometry technique, serum IgG was normal (1388 mg/dl), IgA was high (900 mg/dl), and IgM was also high (517 mg/dl). Advanced and extensive osteolytic lesions were found in the clavicle, ribs, skull, humerus, femur, and columna vertebralis. Plasma cells (myeloma cells) in bone marrow were 32%. The clinical diagnosis was multiple myeloma (biclonal gammopathy) stage IIIB (Durie and Salmon staging system). Clinical response was good after two series of conventional chemotherapy, with normal serum electrophoresis, decreasing serum creatinine and serum calcium. Based on the above data, the diagnosis of multiple myeloma with biclonal gammopathy was confirmed. This is a rare case with a combination of IgA and IgM M-components.