Periosteal chondroma: MR characteristics

Purpose: The purpose of this study was to describe the MR characteristics o f periosteal chondroma. Method: MR images of 12 proven cases of periosteal chondroma were analyzed with reference to tumor. morphology and size. MR features were correlated w ith radiographic and pathologic findings. Results: Tumor size ranged from I to 7 cm in maximum diameter with a mean v alue of l,G cm. On MR images, a soft tissue mass at the bone surface with p ressure erosion of adjacent cortical bone could be identified in all cases. All lesions were bordered by a hypointense rim (100%) and frequently showe d a lobulated configuration (75%). Edema of medullary bone or soft tissues was not observed in any of the cases. Signal intensity of cartilaginous tum or tissue was typically hypo- or isointense relative to muscle on T1-weight ed (100%) and hyperintense relative to fat on T2-weighted (92%) and T2*-wei ghted (100%) MR images. Radiographically significant calcifications of the tumor matrix, present in half of the cases, caused focal signal loss on MR images of all pulse sequences. Contrast enhancement was observed predominan tly at the periphery of the lesions (100%), which on pathologic examination s typically contained fibrovascular bundles, surrounding the cartilage lobu les. Conclusion: Periosteal chondroma appears to have a relatively typical MR ap pearance, which reflects the histologic composition of the lesion. Tn addit ion to radiography, M RI therefore can substantially aid in the preoperativ e diagnosis of this rare bone lesion.