OBJECTIVETo explore the radiological diagnosis of primary malignant fibrous histiocytoma (MFH) of bone.

METHODSSixteen patients with biopsy-or surgery-confirmed MFH received both plain X-ray and CT examinations, among whom six patients simultaneously received MRI. The imaging features were analyzed and the differential diagnoses were assessed.

RESULTS(1) Plain X-ray findings: All these lesions showed irregularly osteolytic, accompanied by cortical destruction. Five patients had varied degrees of cortical expansion, 12 had large soft tissue masses adjacent to the lesions, and only 2 had periosteal reaction. (2) CT findings: All lesions were osteolytic areas but had no evidences that its internal architecture had been replaced by soft tissue mass, and the cortical adjacent to the lesions were permeative osteolysis. Four patients had internal or marginal crest within the lesions and marginal inconsecutive osteosclerosis. Twelve had large soft tissue masses but without any calcification and residual architecture adjacent to the lesions, among which 3 patients had solitary or multiple cystic attenuation areas within the masses. No clear periosteal reaction was observed on CT. (3) MRI findings: All of lesions in 6 patients who received MRI showed inhomogeneous long T1 and long T2 abnormal signal intensity with soft tissue masses adjacent to the osteo-destructions.

CONCLUSIONSThe imaging manifestations of MFH were specific to some extent. Combined utilization of plain X-ray, CT, and MRI is helpful for the diagnosis and differential diagnosis of MFH.