Enchondroma

General characteristics

An enchondroma is a common benign primary osseous tumor; its frequency follows only that of nonossifying fibromas and exostosis.

They are asymptomatic unless they are undergoing malignant transformation or the bone is fractured, and they are often an incidental finding on radiographs.

Benign and malignant chondroid lesions can have a similar appearance, making differentiation of an enchondroma from a low-grade chondrosarcoma difficult or impossible. The presence of a soft tissue mass or a cortical erosion or pain in the absence of fracture, however, increases the likelihood of malignan

Epidemiology

There is no sex predilection, and approximately 50% of these tumors occur in the hands.

Imaging and Location

Enchondromas are typically round or oval lesions with well-defined, lobulated borders. The unmineralized matrix exhibits soft tissue attenuation on CT scans, and homogeneous high signal intensity appears on T2-weighted MR images. Calcification with a ring and arc appearance, which suggests a chondroid matrix, is best identified on plain radiography and CT. Calcifications are not consistently identified with MRI; when seen, however, they have low signal intensity on all sequences.