Case of the week 4.29.19
Publication Date: 2019-04-26
History
8-year-old male castrated Staffordshire terrier. 1 year history of right hind limb lameness
2 images
Findings
Centered over the area of the right stifle, there is a large ovoid to lobular soft tissue mass, with central areas of wispy linear to polygonal mineral opacities, progressive from the referral images. A normal right stifle is not identified. There is complete lysis of the distal half of the femur, the patella, the fabellae, and the proximal half of the tibia and fibula. There is moth-eaten lysis of the proximal half of the diaphysis of the femur, and the distal diaphysis of the tibia and fibula. There is a complete, short oblique fracture of the
distal diaphysis of the tibia and fibula, with mild cranial displacement. Superimposed with the colon at the edge of the field of view and cranial to the pelvic inlet, there is an ovoid heterogenous structure with a thin mineral rim, measuring up to 5 cm in length.
Diagnosis
The large soft tissue mass surrounding the area of the right stifle is most consistent with a joint associated neoplasia (such as synovial myxosarcoma or histiocytic sarcoma). A soft tissue sarcoma with invasion of the underlying bone is also considered.
The ovoid structure with a thin mineral rim in the caudal abdomen may represent a mineralized paraprostatic cyst.
Discussion
The patient didn't have any definitive radiographic evidence of metastasis and is scheduled to undergo an amputation.
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