Intraosseous lipoma of the ilium. A case report.

Intraosseous lipoma is the rarest of the benign primary tumors of bone. It occurs most often in the metaphysis of long bones and is usually identified as an incidental roentgenographic finding. A 53-year-old man demonstrated a mass in his buttock and a lytic lesion of his ilium. Preoperative computed axial tomography (CAT) scanning was helpful in establishing its anatomic boundaries and the cellular composition of the mass. The CAT scan demonstrated the tumor extending anteriorly and posteriorly through the ilium and having a uniform soft tissue density with the same attenuation as adipose tissue. The patient was successfully treated with a marginal excision of the tumor. An intraosseous lipoma seems not to have been previously reported to involve the ilium or be associated with significant extension into soft tissue.