Presentation
Working dog with tail pain of 1 month limiting work for 1 week duration. The dog returned 4 weeks after the initial study with increased tail swelling.
Patient Data
In the 8th coccygeal vertebrae, there is a well-defined, transverse, radiolucent line extending from the ventral cortex dorsally, without extension through the dorsal cortex. Circumferential soft tissue swelling is seen focused at the 8th coccygeal vertebra. No abnormalities are seen associated with the pelvis, hips and imaged portions of femurs.
Subacute, nondisplaced, incomplete fracture of 8th coccygeal vertebra with soft tissue swelling.
There is moderate lysis and widening of the fracture gap with irregularly shaped fracture margins and severe, mixed amorphous and spiculated periosteal reaction. The overall length of the vertebra is shortened, and there is mild angulation centered of the fracture. The circumferential soft tissue thickening is mildly progressive.
Monostotic aggressive bone lesion of the 8th coccygeal vertebra with pathologic fracture. Differential diagnosis includes primary bone neoplasia (e.g. osteosarcoma), multicentric neoplasm (e.g. histiocytic sarcoma, multiple myeloma), fungal osteomyelitis, or metastatic neoplasia.
Case Discussion
Histopathology results: Plasmacytoma of bone suspected to be the cause of a pathologic fracture.
Solitary bone plasmacytomas are less common than multiple myeloma; however, the single lesion in this case designates this as a solitary plasmacytoma of bone. The outcome of these types of tumors in dogs is not well documented, however progression to multiple myeloma and development of additional tumors are possible.
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