A 55-year-old man complains of pain in his back, fatigue and occasional confusion. He admits to polyuria and polydipsia. An X-ray examination reveals numerous lytic lesions in the lumbar veebral bodies. Laboratory studies disclose hypoalbuminemia, mild anemia, and thrombocytopenia. A monoclonal IgG peak is demonstrated by serum electrophoresis. Urinalysis shows 4+ proteinuria. A bone marrow biopsy discloses foci of plasma cells, which account for 18% of all hematopoietic cells. What is the appropriate diagnosis?
High-Yield Explanation
Plasma cell myeloma (multiple myeloma) is characterized by a multifocal infiltration of malignant plasma cells in the bone marrow. Major diagnostic criteria for plasma cell myeloma include marrow plasmacytosis (>30%), plasmacytoma on biopsy, and immunoglobulin paraprotein (M-component). In this patient, the neoplastic clone secretes excess kappa light chains. Waldenstrom macroglobulinemia is a neoplastic disorder of small lymphocytes that secrete IgM.Diagnosis: Multiple myeloma