A closer view of the stromal cells shows their spindled appearance without any ominous or atypical, cytologic characteristics. This bland appearance is the reason the diagnosis is often not appreciated on initial biopsy. This medium-power photomicrograph shows the features of a dedifferentiated, parosteal osteosarcoma. The pattern of the trabeculae is similar, but the stroma now is composed of a highly-cellular tissue with cells of many different shapes and forms, i.e., pleomorphic. A closer view shows the pleomorphic, hyperchromatic, neoplastic cells with a great deal of cellular atypia.
Marginal excision leads to frequent, local recurrence.
This shows the appearance of the resection site after a wide resection of a parosteal osteosarcoma of the distal femur. This is the postoperative, radiographic appearance of the reconstruction using two, autogenous, cortical grafts to span the defect and achieve an arthrodesis. The appearance and function at follow up four years later was satisfactory. The lesion is unresponsive to radiation therapy.