IS Case 8: Multiple Myeloma
Imaging Sciences URMC 2008
Publication Date: 2009-05-18
A 59-year-old male presents from outside institution with initial complaint of lower back pain. Outside plain film of lumbar and thoracic spine display osteopenia with compression fracture of T8. Follow up MRI displayed expansile, enhancing lesion of T8 as well as extensive involvement of multiple ribs and thoracic/lumbar vertebral bodies which was suggestive of mets of unknown primary or myeloma.
The incidence of multiple myeloma is 4.4 per 100,000 people and is the most common primary malignant bone tumor. Men are roughly 50% more likely to have this disease, than women. 99% of cases occur after the age of 40. There are a few common clinical presentations including: back pain (especially with heavy activity), fatigue secondary to anemia, neurologic symptoms secondary to hypercalcemia, recurrent infections and pathologic fracture. Patients may also be discovered before symptoms begin when labs are drawn and an incidental finding of hyperproteinemia is identified. In order to diagnose myeloma with certainty three criteria must be fulfilled including: 1) Positive radiographic survey; 2) Monoclonal hypergammaglobulinemia (IgG > IgA most commonly); 3) >10-15% bone marrow aspirate demonstrating plasma cells. Many other labs are associated with multiple myeloma but these are the main criteria.
Radiographically there are few common presentations that include: 1) Diffuse loss of bone density and altered bone texture; 2) Multiple "punched-out" lytic lesions in characteristic locations (HALLMARK); 3) Solitary lytic lesion (plasmocytoma); 4) Sclerotic lesions (Sclerosing myelomatosis in less than 1% of cases); 5) Soft tissue masses; 6) Normal. A skeletal survey with plain film examination is the study of choice for examining myeloma. Common films include 1) Lateral Skull; 2) AP of Humerus, Pelvis, Ribs, Femur; 3) AP & Lateral of Spine. Most common locations for lesions include the 1) Skull, Ribs, Sternum, Spine, Pelvis (and less frequently) 2) Femur, Humerus, Forearm, Lower Leg, Mandible. Limitations of skeletal survey include 30% cortical bone loss necessary to identify a lytic process and concominant osteoporosis evident in the elderly population. Bone scan is normally negative in these patients since osteoclastic activity predominates and osteoblastic activity is necessary in order to show up on bone scan. This fact can be useful to differentiate multiple myeloma from lytic metastases since metastases will more likely yield a positive bone scan. Another useful differentiating factor is that the vertebral pedicles are sometimes spared early in multiple myeloma secondary to lower levels of red marrow in the pedicles while metastatic disease affects the pedicles and vertebral bodies equally.
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