Osteosarcoma displays disorderly growth of atypical hyperchromatic and pleomorphic tumor cells. Mitotic figures are present in both the immature, central portion of myositis ossificans and osteosarcoma, but myositis ossificans lacks the atypical or tripolar mitotic figures characteristic of osteosarcoma. Diagnostic problems may arise in myositis ossificans if a biopsy is small and taken only from the central area in the early proliferative phase, as this may lead to confusion with osteosarcoma or a soft tissue sarcoma. An adequate open biopsy will display the zoned pattern and exclude malignant entities from consideration. Because myositis ossificans is a benign self-limiting process, the prognosis is excellent.
Local excision is curative.
Soft tissue tumors. Mosby, St. Louis, co. 1995, pp.