Presentation
Bilateral knee pain when weight-bearing. Known history of fibromyalgia.
Patient Data
A lesion with irregular calcification is noted on the distal metaphysis of the right femur. There is no cortical breach. There is no endosteal scalloping. There is no periosteal reaction.
Findings are suggestive of an enchondroma.
Case Discussion
Enchondromas are somewhat common benign cartilaginous tumors. They are usually seen in the small tubular bones of the hands and feet, but they can also be found in large tubular bones.
Typically, enchondromas will have a distinct radiographic depending on whether they are present in a small or large tubular bone.
In large tubular bones, such as in this case, they usually present with a chondroid matrix and no aggressive features such as endosteal scalloping, periosteal reaction, or cortical disruption.
If aggressive features are present, low-grade chondrosarcoma is an important differential diagnosis.