Primary Osteosarcoma of the Bone with Rhabdoid Features: A Rare, Previously Undescribed Primary Malignant Tumor of Bone.

Primary osteosarcoma of the bone with rhabdoid features is a rare malignant tumor of bone, not previously described in the literature. Here we report a 69-year-old female who originally presented with a right femur pathologic fracture. Radiographs of the injury showed an aggressive-appearing lesion of the distal femur. Initial biopsy was done, which was not diagnostic; additional advanced imaging studies were performed, which failed to show any other site within the body with detectable disease process. Accordingly, the patient underwent radical resection of the distal femur and reconstruction with endoprosthesis. Histopathology obtained from the operative specimen showed osteosarcoma with rhabdoid features. Two months after surgery, the patient is symptom-free and doing well; she is currently pending adjuvant chemotherapy. Although rhabdoid features have been described in extraskeletal osteosarcoma, this appears to be the first mention of osteosarcoma of bone with rhabdoid features in the literature.