Diagnosis and Outcome of Periosteal Chondrosarcoma in Two Cats.

Two cats, both over 10 yr old, were presented for evaluation of non-painful bony proliferations on the appendicular skeleton. These proliferations were identifiable via palpation. Radiographs showed a smooth, proliferative bony lesion of the distal femur (case 1) and tarsus (case 2) with mild soft tissue swelling. Surgical debulking with incomplete resection was performed in each cat. Subsequent histopathology resulted in a diagnosis of periosteal chondrosarcoma (PC). Although both cats have experienced local recurrence, both are still alive more than 2.5 yr after mass debulking. Periosteal chondrosarcoma is a differential diagnosis in proliferative cortical bony lesions near an articular surface in older cats. Partial resection of these masses can lead to an excellent quality of life, and proper diagnosis can avoid amputation or even euthanasia.