MR Imaging Findings of Intraosseous Lipoma

ABSTRACT

PURPOSE: To evaluate the MR imaging findings of intraosseous lipoma. MATERIALS AND METHODS: The MR imaging findings of 12 cases of intraosseous lipoma were retrospectively analyzed with regard to internal signal intensity, enhancement patterns, the presence of calcification and the status of the margin. The findings relating to these last two features were compared with those of plain films and CT. RESULTS: Six tumors were located in the calcaneus, three in the tibia, two in the ilium, and one in the carpal lunate. A fat component was clearly identified in all cases, but no lesion was purely fatty. Cyst formation was noted in four cases, and hyperintense portions different from the cystic area were seen on T2WI in ten. Contrast enhancement was observed in four patients, and although plain film and CT images revealed, in all cases, the presence of calcification, in two cases this was not demonstrated by MRI. In all cases, however, MRI showed well-defined tumoral margins. CONCLUSION: MRI clearly depicts fat and other components related to the involutional changes occurring in cases of intraosseous lipoma. The information these images provide is useful for the diagnosis and histologic classification of intraosseous lipoma.