Review Question - QID 383

This patient's history, imaging, and biopsy are consistent for osteosarcoma.

The patient's biopsy specimen displays a high grade osteosarcoma with atypical nuclei and mitoses present, and therefore is a II as there is no evidence of metastasis (Low grade= I and High grade=II, presence of metastases=III). The question stem states the lesion is extracompartmental on MRI as the tumor has eroded through the cortical bone and breached the "compartment" of the femur and is therefore a B (Intracompartmental=A, Extracompartmental=B). Therefore this patient has a IIB osteosarcoma of the distal femur. It is not a 2B, as the lesion is malignant. The Enneking staging system for benign lesions is detailed with Arabic numerals (1=inactive, 2=active, and 3=aggressive).

The article by Meyers et al revealed that adjuvant chemotherapy improves disease-free survival (DFS) for patients with osteosarcoma. They found that the 5-year DFS was 76% for patients aged less than or equal to 21 years.

A table showing the Enneking classification system is shown in illustration A. A gross pathology picture taken of this patients extirpated osteosarcoma is shown in Illustration B.