MRI Appearance of Enchondroma

Enchondromas may be incidentally seen on MRI. They are lobulated with multiple thin septa, low to intermediate signal intensity on T1-weighted images, and hyperintense on T2-weighted images. Calcifications may be seen as signal voids on all sequences. Contrast enhancement in rings and arcs is seen.

The main differential consideration is a low-grade chondrosarcoma, which may have similar findings. Patients with chondrosarcoma will often have pain, but so will a number of patients with enchondroma. Findings that help differentiate the two are:

• Deep endosteal scalloping: Chondrosarcomas tend to demonstrate endosteal scalloping greater than two-thirds of cortical thickness
• Extensive endosteal scalloping: The longer the extent of endosteal scalloping relative to lesion length, the more likely is it for the lesion to represent chondrosarcoma.
• Cortical destruction
• Soft-tissue mass
• Periosteal reaction
• Marked uptake of radionuclide: Chondrosarcomas tend to demonstrate uptake greater than the anterior iliac crest on bone scan.

References

Murphey MD, Flemming DJ, Boyea SR, Bojescul JA, Sweet DE, Temple HT. Enchondroma versus chondrosarcoma in the appendicular skeleton: differentiating features. Radiographics. 1998 Sep-Oct;18(5):1213-37;