Imaging features of chondromyxoid fibroma: report of 15 cases and literature review.

OBJECTIVE:: Chondromyxoid fibroma (CMF) is a rare benign bony tumour. Our objectives are three-fold: first, comparing MRI, conventional radiography (CR) and CT characteristics of CMF; second, providing a literature review; and third, summarizing the role of imaging landmarks in the differential diagnosis with other bony lesions.

METHODS:: 15 patients with histopathologically proven CMF were retrospectively included. MR images were reviewed for typical findings and compared with imaging features on CR and CT.

RESULTS:: All lesions were isointense on T1 weighted images with a low intensity rim in nine cases corresponding to the perilesional sclerosis on CR and CT. Internal trabeculations were more prominent on CR than on CT due to corrugation and scalloping at the tumour's edge. CT was superior to CR in analysing the expansion of the lesion, cortical breakthrough and internal mineralization. T2 short tau inversion recovery or T2 weighted fat saturation images showed an intermediate to hyperintense signal in all lesions, mostly heterogeneous. Some lesions contained small internal cysts, and one lesion demonstrated a low signal intensity centrally, corresponding to internal mineralization on CT. Intense contrast enhancement was present in all lesions. Minimal bone and soft tissue oedema were seen in, respectively, six and three patients.

CONCLUSION:: The diagnosis of CMF is difficult because of overlap of characteristics with other bony lesions. Our comparative study puts forward advantages and limitations of different imaging modalities in the diagnosis of CMF.

ADVANCES IN KNOWLEDGE:: For the first time, imaging features of CMF are analysed and compared on CR, CT and MRI.