Radiology Case
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Radiographic findings: There
is severe soft tissue swelling surrounding the stifle joint. The swelling
is both intracapsular and extracapsular and extends to the level of the
proximal tibia. There are multiple areas of bony lysis involving the proximal
tibia, distal femur, patella, and gastrocnemius fabellae.
Radiographic impression: The radiographic findings are highly suggestive of a soft tissue neoplasia such as a synovial cell sarcoma.
Comments: The radiographic
changes in this case may also be seen with fibrosarcoma, metastatic neoplasia,
and unlikely multicentric osteosarcoma. Biopsy of the region is necessary
to confirm the diagnosis. Synovial cell sarcomas typically affect middle
aged to older dogs that are large but not giant breeds. Males are more
commonly documented than females. The patients generally present with
a palpable soft tissue mass and/or signs of lameness. The most common
joints presented are the stifle, the tarsus, and the elbow; several other
sites have also been reported.1 Interestingly, synovial cell sarcomas
arise from periosteal connective tissues and not from the synovial membrane.
Metastatic rates are variable to the lungs and local lymph nodes. Amputation
and chemotherapy have been utilized in the treatment of this disease.1,2
References
- Withrow S, LaRue S. Tumors of the skeletal system In: Withrow S and MacEwen G, eds. Clinical veterinary oncology. Philadelphia: Lippincott, 1989;244-245.
- Ogilvie GK, Moore AS. Bone tumors In: Stone KL, ed. Managing the veterinary cancer patient : a practice manual. Trenton, NJ: Veterinary Learning Systems, 1995;452-468.
Dr. John Feleciano, DVM, DACVR
Dr. Renee Leveille, DVM, DACVR