A 13 year-old male castrated domestic shorthair cat presented to Cornell's Oncology Service for evaluation of a mass on the left pelvic limb. He had a two-week history of lameness prior to presentation. On physical examination, there was a firm, fixed mass on the medial aspect of the left caudal thigh. Pain was elicited on palpation of the affected limb. The left popliteal lymph node was moderately enlarged. No other abnormalities were noted on exam. Radiographs of the limb revealed a bony proliferative lesion in the distal diaphysis of the tibia with two nodules in the surrounding soft tissue. An aspirate of the mass was suggestive of a sarcoma and the left hind limb was amputated. Initial histopathological analysis revealed a completely excised suspect high-grade sarcoma, which was later amended to primary bone tumor. This paper provides an overview of feline soft tissue sarcomas, including histological features, treatment options and prognostic indicators.