Periosteal chondroid tumors: Radiologic evaluation with pathologic correlation

OBJECTIVE. The purpose of this study was to determine whether the imaging f eatures of periosteal chondroid tumors correlate with histopathology. MATERIALS AND METHODS. Twenty-two patients (nine women and 13 men; mean age , 33 years) with pathologically proven periosteal chondroid lesions were re trospectively reviewed. The imaging modalities included conventional radiog raphy (n = 17), CT (n = 10) and MR imaging (n = 14). The images were review ed by two osteoradiologists, with agreement by consensus. Evaluation criter ia included lesion location, mineralization, and sized periosteal reaction, and cortical response. Intramedullary extension, adjacent intramedullary e dema, soft-tissue edema. and intrinsic characteristics were also evaluated on MR imaging. After the evaluation, a radiologic diagnosis of chondroma or chondrosarcoma was obtained. An experienced osteopathologist who was unawa re of the patient's medical history and radiologic findings reviewed all hi stopathology. Agreement between the radiologic and the histopathologic diag nosis was tested using the kappa analysis. Imaging features were correlated with the pathologic findings, and a statistical analysis was performed. RESULTS. Using strict pathologic criteria, we diagnosed 11 chondromas and 1 1 chondrosarcomas (nine, grade I; two, grade II). Moderate agreement was re ached between the radiologic and the pathologic diagnosis (kappa = 0.55). T he size of periosteal chondrosarcomas (range, 3-14 cm; median, 4 cm) was co nsiderably larger than the size of the chondromas (range, 1-6.5 cm; median, 2.5 cm; p < 0.05). Other imaging features did not significantly correlate with benign versus malignant disease at pathology (all p > 0.05). CONCLUSION. A variable overlap existed in the imaging appearances of benign and malignant periosteal chondroid lesions, with size being the most relia ble indicator in distinguishing the two lesions. This and the fact that his tologic differentiation of the entities can be difficult, suggests that sur gical wide excision may be the most appropriate procedure in treating patie nts with lesions greater than 3 cm.