Chondrosarcoma is the most common malignant bone tumor in the foot in some reported series. The peak age of presentation is in the 50's and 60's. Patients with multiple cartilage lesions, such as Ollier's disease, or multiple enchondromas are at increased risk. The lesion presents as a slow growing mass with mild pain.

This tumor has several subtypes, including clear cell chondrosarcoma, and mesenchymal chondrosarcoma, which can occur in bone (images 1, 2, 3, 4) in the soft tissues (image 5), where it presents as as an innocent bump.

The radiographs will show a lytic lesion which may demonstrate ring and arc formations. Cortical expansion, breakthrough, and a soft tissue mass are signs of malignant behavior.

MRi shows high signal intensity on T2 sequences, and low intensity signal on T1 sequences. Calcification within the mass, if it occurs, will appear as very low signal areas.

Most chondrosarcomas are low grade, but dedifferentiated chondrosarcoma can occur in the setting of a longstanding benign cartilage lesion such as enchondroma.

Treatment for low grade chondrosarcoma may include curettage or marginal excision. Intermediate and high grade lesions should be excised with a wide margin. Clear margins are essential, because no truly effective adjuvant therapy exists.

Chemotherapy and radiotherapy are not effective and are normally not used for lesions in the foot. Rather, complete removal with a wide margin is the correct treatment. Amputation of the affected part is employed if necessary to achieve a wide margin. Incompletely excised lesions should be referred to a musculoskeletal oncologist for re-resection.

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