extraskeletal osteosarcoma

Definition: Extraskeletal osteosarcoma (ESOS) is a rare soft tissue sarcoma, typically characterized by a bone-producing neoplasm.

ESOS is a rare malignant mesenchymal neoplasm, accounting for 1% 2% of all soft tissue sarcomas.

The tumor is located in soft tissue, without attachment to skeletal bones as determined by radiographic examination or inspection during surgery.

The vast majority of ESOS cases published in the literature was typically characterized by high-grade histological features and prone to local recurrence and distant metastasis and have poor prognosis.

LGESOS is extremely rare. In 1953, Umiker first reported 1 cases of LGESOS, so far only 10 cases have been reported until 2015, including 3 male patients and 7 female patients; the mean age was 51.4 years old (range 30 77 years).

The minimum size of tumor was 5 cm × 3 cm × 2 cm, and the maximum size of tumor was 30 cm × 18 cm × 5 cm; the primary tumor site: 2 cases in the thigh, 2 in the leg, 1 in the popliteal fossa, 1 in the axillary, 1 in the back, 1 in the anterior mediastinum, 1 in the abdominal cavity, and 1 in the left shoulder. One case died in 12 months after diagnosis due to huge unresectable tumor. The other 9 cases were underwent tumor resection, and only 1 case was treated with chemotherapy after surgery. Five cases were free of disease after follow-up for 2, 12, 24, 47, and 60 months, respectively. The other 4 cases died of tumor extensive metastasis after operation for 4, 33, 48, and 48 months, respectively.

Variants

 low-grade extraskeletal osteosarcoma (LGESOS)

• LGESOS is an extremely rare soft tissue tumor, and patients with LGESOS tend to have a better prognosis.
• LGESOS can arise in the mediastinum with lung metastasis.