Abstract
Chondrosarcomas are malignant neoplasms of mesenchymal origin that typically arise from flat bones, and to a lesser degree, long bones. These tumors may be categorized as primary or secondary dependent upon the source. Locally invasive behavior is characteristic of this type neoplasm.1
A 24-year-old female California Sea Lion (Zalophus californianus) housed at the Miami Seaquarium, had exhibited lameness on the left front flipper and swelling of the left shoulder. She was sedated with 0.1 mg/kg Versed IM and reversed with an equal volume of Romazicon IM. The shoulder joint and humerus were locally anesthetized using 10 cc lidocaine and 10 cc Marcaine. Radiographs of the left shoulder were taken. Analysis of the radiographs showed a rounded, radiolucent bony mass surrounding 2/3 of the left humerus.
A bone biopsy and bone marrow aspirate samples were obtained and submitted to Northwest ZooPath for further evaluation. Histopathology revealed changes consistent with a chondrosarcoma. The atypia exhibited by the chondrocytes made malignancy likely and typically malignant tumors of cartilage are invasive and have potential for metastasis.
Due to advanced age, amputation of the affected limb was not viewed as a viable treatment option. This condition has been managed with long-term anti-inflammatory and antibiotic therapy. This case exemplifies the successful long-term (> 2 years) palliative care of a locally aggressive neoplasm as a viable therapeutic option. A previous case of an extraskeletal chondrosarcoma in a California Sea Lion has been reported.2 The authors are previously unaware of another case of a primary skeletal chondrosarcoma in a California Sea Lion.
* Presenting author
Literature Cited
1. Beck AP, Jones ML. Chondrosarcoma of the scapula of an 8-month-old Holstein steer. Journal of Veterinary Diagnostic Investigation. 2012;24(4):791–793.
2. Dalton LM, Mathey WS, Crawley RR. Chondrosarcoma in a California sea lion (Zalophus californianus). In: Proceedings from the International Association of Aquatic Animal Medicine Conference; 1992.