A 15-year-old male domestic shorthair cat was presented with a mass over the left ilium.
Computed tomography showed an osteolytic lesion originating from the left ilial wing with soft tissue invasion but no pulmonary metastasis. Cytology was consistent with a sarcoma, with axial osteosarcoma most likely. A partial cranial internal hemipelvectomy was performed, preserving the left pelvic limb and the caudal sacroiliac joint. Histopathology confirmed a poorly differentiated chondroblastic osteosarcoma with a mitotic count of 61 per 2.37 mm2. Surgical margins were clear, with a minimum 9-mm tumour-free margin.
The cat recovered well, resumed normal activity by 3 weeks, and had no lameness. Adjuvant carboplatin chemotherapy was administered 20 days postoperatively and was continued for six cycles. Follow-up thoracic radiographs at multiple intervals showed no metastasis, and pelvic radiographs at 6 months revealed no local recurrence or pelvic disruption.
At 473 days postsurgery, the cat remained active and disease-free. This case supports partial cranial internal hemipelvectomy as a viable option for feline ilial wing osteosarcoma.
