Aneurysmal bone cyst in the pelvis of a cat: successful outcome of partial iliectomy with limb preservation

Case summary A 3-year-old spayed female domestic shorthair indoor cat presented with a 3-week history of pain from the pelvic region. Physical examination revealed pain elicited on palpating the pelvic area and right hip. Radiographs and CT showed an expansile, osteolytic process with intact cortex in the right wing of the ilium. CT revealed a monostotic and soft tissue-attenuating process with clear margins. Preoperative histopathological diagnosis of aneurysmal bone cyst was made from incisional biopsies. The cyst was removed en bloc with limb-sparing partial iliectomy. Histopathology confirmed the diagnosis of aneurysmal bone cyst. Recovery from surgery was uneventful. At re-examination 8 weeks and 8 months postoperatively, the cat was pain free and physical examinations were within normal limits. Relevance and novel information Feline aneurysmal bone cysts are rare and reported cases are few. To our knowledge, this is the first report describing the CT appearance of a pelvic aneurysmal bone cyst and partial iliectomy with limb preservation in a cat with successful short-term outcome.