Chondrosarcoma

A firm mass projected from the deltoid muscle region of a 24-year-old man's right shoulder. The patient stated that the mass, which had been present “for years,” had always been firm and immobile. Three months before seeking evaluation, the patient's upper right arm and shoulder became painful and the mass grew more prominent (A).

A radiograph demonstrated a 10-cm lobulated and calcified mass centered in the metaphyseal region of the proximal humerus. The lobulations contained the arc and ring pattern typical of a cartilaginous neoplasm (B). A nuclear medicine bone scan and a full-body skeletal survey demonstrated no additional lesions. The mass was resected; the proximal and mid humerus were removed as well (C).

Examination of a specimen from a frozen section of the neoplasm revealed a low-grade chondrosarcoma, which arose within an existing osteochondroma. The average size of a chondrosarcoma that arises from an enchondroma, or a benign growth of cartilage within bone, is 5 to 6 cm or greater. Clinically, malignant transformation is suspected when:

• The lesion enlarges rapidly.
• The patient complains of pain.
• An ultrasound or MRI scan shows the lesion's cartilage cap is greater than 1 to 2 cm.

The treatment of chondrosarcoma is determined by the stage of the neoplasm; the prognosis largely depends on the tumor's grade. Resection is the treatment of choice for localized tumors; chemotherapy and radiation therapy have no role if, as in this case, the tumor is resectable.

An osteoarticular allograft was used to reconstruct the patient's humerus. He will undergo follow-up MRI examinations at 3 and 6 months, and 1 and 2 years after tumor resection. Evaluations will then be scheduled every 2 to 4 years and may continue for 10 years after resection.