Imaging of primary tumors of sacrum

Abstract

Conventional radiology plays a minimum role in identifying bone tumors of the sacrum in the initial stage since sacrum is a curved bone and often is obscured by overlying intestinal contents. Sacrum is composed of two distinct tissues, which include osseous and neural. This paper deals with osseous tumors only. Primary tumors of the sacrum may be benign or malignant. In malignant tumors soft tissue component is more prominent. As elsewhere, age is important in deciding whether the tumor is benign or malignant. Benign tumors include osteoid osteoma, osteoblastoma, osteochondroma, giant cell tumor and aneurysmal bone cyst. Malignant tumors include chordoma, osteosarcoma, Ewing sarcoma, chondrosarcoma, plasmacytoma and malignant fibrous histocytoma. Primary lymphoma of sacrum is very rare. Plain radiographs depict osteolysis, osteosclerosis and expansion of the bone with soft tissue swelling with mineralisation. Advanced imaging may be necessary in arriving at a final diagnosis. Imaging characteristics are described with the help of illustrations. Neurogenic tumors secondarily involving the sacrum are not included in this paper.

Keywords

• sacrum
• benign
• primary malignant
• neoplasms
• tumors