Primary vertebral osteosarcoma: imaging findings.

Abstract

To evaluate patient age and sex and location and imaging appearances of primary vertebral osteosarcoma (PVOS) compared with histologic subtypes. Retrospective review (1915-2001) of imaging findings in patients with histologically proved primary osteosarcoma of vertebral column was performed. Two radiologists in consensus reviewed findings for location, origin site, matrix pattern, and spinal canal invasion and compared them with histologic subtypes. Radiation-induced, Paget, metastatic, and multifocal osteosarcoma were excluded. Of 4,887 osteosarcoma cases, 198 (4%) were PVOS arising from vertebral column. There were 103 female and 95 male patients (age range, 8-80 years; median age, 34.5 years). Involvement included cervical (27 patients), thoracic (66 patients), lumbar (64 patients), and sacral (41 patients) spine. Adequate imaging findings were available in 69 patients, and involvement of two levels was seen in 12 (17%). In nonsacral spine, most tumors (44 cases) arose from posterior elements, with partial involvement of vertebral body. Lesions confined to vertebral body were less frequent (12 cases). Sacral tumors involved body and sacral ala. The most common histologic subtypes were osteoblastic (47 patients), chondroblastic (12 patients), telangiectatic (four patients), fibroblastic (four patients), small cell (one patient), and epithelioid (one patient). The majority (55 cases) demonstrated osteoid matrix mineralization; 17 showed marked mineralization. Five cases with marked mineralization were confined to vertebral body, with "ivory vertebra" appearance. Purely lytic pattern was seen in 14 (20%) cases. Lytic pattern was seen in four (100%) telangiectatic, three (75%) fibroblastic, three (25%) chondroblastic, three (6%) conventional osteoblastic, and one (100%) small-cell subtypes. Invasion of spinal canal was common (84% of cases). Appearance simulating osteoblastoma without soft-tissue mass was present (seven cases). Pathologic compression fractures were identified (seven patients). This study provides age and sex distribution and location and imaging features in a large series of PVOS.