OBJECTIVETo investigate the imaging feature of primary malignant fibrous histiocytoma of the bone (PBMFH) by the conventional radiography, CT and MRI, and to evaluate these different imaging methods in its diagnosis.

METHODSThe imaging data of conventional radiography, CT and MRI of 35 patients with pathologically confirmed PBMFH were retrospectively analyzed.

RESULTSThough the imaging appearance of PBMFH varied in different cases, all the imaging findings of malignant bone tumors were revealed. The common imaging appearance on the conventional radiography and CT were eccentric, aggressive, osteolytic destructions of various types located at the ends of extremities with extraosseous soft tissue masses, but periosteal reaction was rare. Heterogeneous signal intensities on T(1)WI and T(2)WI were common MRI changes but not specific.

CONCLUSIONPrimary malignant bone fibrous histiocytoma, a rare primary malignant bone tumor, is most frequently located in the long bone. Conventional radiography is still the first and main choice and is taken as an essential means of diagnosis. CT and MRI are quite important in demonstrating the details and extent of the disease such as soft tissue, cortical destruction, periosteal reaction, calcification and necrosis. The imaging characteristics may be of value in differentiating MFH from the other malignant bone tumors. Furthermore, MRI may also be valuable in assessing the efficacy of chemotherapy and/or radiation therapy, as well as in distinguishing recurrence from postoperative or post-radiation changes.