A 69-year-old woman is brought to the emergency room after falling off a step stool and fracturing her hip. Her past medical history is significant for several bouts of pneumonia during the past year. Laboratory results indicate a normal white blood cell count, but platelets are decreased, and the erythrocyte sedimentation rate (ESR) is elevated. X-rays reveal multiple lytic bone lesions. Serum electrophoresis demonstrates an M-protein spike. Which of the following is the MOST likely diagnosis?
The patient is suffering from multiple myeloma, a neoplastic proliferation of plasma cells (or their precursors) found within the bone marrow. These malignant cells are responsible for the production of excessive amounts of immunoglobulin (usually IgG or IgA), producing an M- protein spike, and increasing the ESR. The decreased platelet count probably reflects infiltration of the bone marrow by myeloma cells. It is not unusual for patients with malignant myeloma to have recurring bacterial infections, paicularly pneumococcal pneumonia, because the overall production of normal immunoglobulins of all isotypes is decreased. Lytic bone lesions due to infiltration by myeloma cells may lead to pathological fractures. All of the other disorders listed can be associated with an M-protein spike, but this is a nonspecific finding. Chronic lymphocytic leukemia (CLL) is ruled out by the normal white count, since this type of leukemia is generally associated with an absolute lymphocytosis. Patients with monoclonal gammopathy of undetermined significance are generally asymptomatic, although they have a predisposition for subsequently developing myeloma, lymphoma, amyloidosis, or Waldenstrom's macroglobulinemia. Plasmacytoma (solitary myeloma) is a rare, isolated plasma cell neoplasm in bone or soft tissues. If the primary cancer is in bone, it is likely to disseminate; extraosseous tumors tend to remain localized. Since this patient had multiple lytic bone lesions, multiple myeloma is the correct diagnosis. Ref: Chandrasoma P., Taylor C.R. (1998). Chapter 30. The Lymphoid System: III. Plasma Cell Neoplasms; Spleen & Thymus. In P. Chandrasoma, C.R. Taylor (Eds), Concise Pathology, 3e.
Chronic lymphocytic leukemia
Monoclonal gammopathy of unceain significance
Multiple myeloma (plasma cell myeloma)
Plasmacytoma