A 79-year-old man presents with increasing thoracolumbar pain and difficulty straightening his back. He denies having radiating pain down the legs. He also denies a history of cancer or recent, significant weight loss. Lateral radiograph (Figure 1) and sagittal MRI (Figure 2) show new wedge compression fractures at T11, T12, and L1. The heterogeneous signal in the marrow at these levels suggests subacute fractures. His DXA shows a T score of -3.7 at the lumbar spine (L1-L4), which has decreased by 25% since his last DXA 8 years ago. Labs show a calcium of 9.9 (nl 8.2 to 9.8 mg/dl), elevated alkaline phosphatase of 133 (nl 45 to 117 U/L), an intact parathyroid hormone (PTH) of 10.8 (normal 11.1 to 79.5 pg/ml), and a vitamin D of 28.7 (normal 30 to 100 ng/ml). He was also found to have an elevated calcium level in his 24-hour urine collection.
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A pathologic fracture should always be considered in the differential diagnosis when a patient presents with a new compression fracture. This patient has severe osteoporosis at the lumbar spine, which is likely the cause of his compression fractures. However, the cause of his poor bone quality is unclear. His slightly elevated serum calcium level, elevated urine calcium level, and elevated alkaline phosphatase is concerning for a destructive pathologic lesion (when bone breaks down calcium and alkaline phosphatase is released). Multiple myeloma, which frequently presents with bony involvement, should be ruled out in this patient before assuming his osteoporosis is age related or caused by low vitamin D level.
Multiple myeloma is the most common primary bone malignancy. Up to 80% of newly diagnosed multiple myeloma patients will have bony involvement, and the spine is the most common site involved. The malignant plasma cells of multiple myeloma invade bone and increase osteoclastic activity causing osteoporosis in the spine. MRI is the most sensitive diagnostic test to detect multiple myeloma, although lesions may not show on MRI early in the disease. Early detection of multiple myeloma may be accomplished through blood testing, including a serum protein electrophoresis (SPEP). A monoclonal spike on SPEP is consistent with multiple myeloma. A bone marrow biopsy may be necessary to detect an increase in plasma cells in bone marrow, which is diagnostic of multiple myeloma. Ordering a sestamibi for suspected parathyroid disease is incorrect because hyperparathyroidism would present with an elevated intact parathyroid hormone.1,2
Dagan Cloutier, MPAS, PA-C, practices in a multispecialty orthopedic group in the southern New Hampshire region and is editor-in-chief of the Journal of Orthopedics for Physician Assistants (JOPA).
- Tosi P. Diagnosis and treatment of bone disease in multiple myeloma: spotlight on spinal involvement. Scientifica (Cairo). 2013;2013:104546.
- O’Donnell P. Multiple myeloma. https://www.orthobullets.com/pathology/8024/multiple-myeloma. Accessed on February 13, 2018.