AAOS Ch 4 Onco Flashcards
A 16-year-old girl has had pain in the left groin for the past 4 months. She notes that the pain is worse at night; however, she denies any history of trauma and has no constitutional symptoms. There is no history of steroid or alcohol use. Examination reveals pain in the left groin with rotation of the hip. There is no associated soft-tissue mass. A radiograph and MRI scan and biopsy specimens are shown. What is the most likely diagnosis?
1: Clear cell chondrosarcoma
2: Chondroblastoma
3: Giant cell tumor
4: Aneurysmal bone cyst
5: Osteonecrosis of the femoral head
2: Chondroblastoma
Based on the epiphyseal location and sharp, well-defined borders, the radiograph suggests chondroblastoma. Histologically, multinucleated giant cells are scattered among mononuclear cells. The nuclei are homogeneous and contain a characteristic longitudinal groove. Although not seen here, “chicken-wire calcification” with a bland giant cell-rich matrix is also typical for chondroblastoma. Clear cell chondrosarcoma occurs in epiphyseal locations but has a more aggressive histologic pattern and occurs in an older age group. Giant cell tumors occur in the epiphysis but have a more uniform giant cell population histologically. Aneurysmal bone cyst often results in bone remodeling and has a different pathologic appearance. Osteonecrosis has a typical histologic pattern of empty lacunae and necrotic bone.
A 19-year-old girl has had pain and swelling in the right ankle for the past 4 months. She denies any history of trauma. Examination reveals a small soft-tissue mass over the anterior aspect of the ankle and slight pain with range of motion of the ankle joint. The examination is otherwise unremarkable. A radiograph and MRI scan and biopsy specimens are shown.
What is the most likely diagnosis?
1: Osteogenic sarcoma
2: Ewing sarcoma
3: Giant cell tumor of bone
4: Aneurysmal bone cyst
5: Metastatic adenocarcinoma
3: Giant cell tumor of bone
Giant cell tumors typically occur in a juxta-articular location involving the epiphysis and metaphysis of long bones, usually eccentric in the bone. The radiographs show a destructive process within the distal tibia and an associated soft-tissue mass. The histology shows multinucleated giant cells in a bland matrix with a few scattered mitoses. Osteosarcoma can have a similar destructive appearance but a very different histologic pattern with osteoid production. Ewing sarcoma also can have a diffuse destructive process in the bone. The histologic pattern of Ewing sarcoma is diffuse round blue cells. Aneurysmal bone cysts typically are seen as a fluid-filled lesion on imaging studies and have only a scant amount of giant cells histologically. Metastatic adenocarcinoma does not demonstrate the pattern shown in the patient’s histology specimen.
A 10-year-old child reports acute leg pain after wrestling with his brother. AP and lateral radiographs are shown. What is the best course of action?
1: Biopsy, curettage, and plating
2: Wide segmental resection
3: Hip disarticulation
4: Closed reduction and a long leg cast
5: Tibial traction and MRI
4: Closed reduction and a long leg cast
The radiographs show an eccentric metaphyseal lesion with a well-defined reactive rim of bone that is consistent with a nonossifying fibroma. Pathologic fractures through benign lesions should be treated as appropriate for the fracture, allowing the fracture to heal. Biopsy is not needed when the radiographic diagnosis is benign. MRI, in the presence of a fracture, is not particularly helpful because of the hematoma. If radiographic findings reveal that the lesion appears aggressive, a biopsy should be performed, obtaining tissue away from the fracture site.
A 20-year-old patient has foot pain. A radiograph and T1-weighted MRI scan and a biopsy specimen are shown. Treatment should consist of
1: extended curettage and cementation.
2: amputation of the first ray.
3: wide resection and chemotherapy.
4: extended curettage, radiation therapy, and chemotherapy.
5: Syme amputation.
1: extended curettage and cementation.
Giant cell tumors occur near articular surfaces in young adults. The histology shows abundant giant cells with nuclei resembling the surrounding cells. Although the MRI scan shows soft-tissue involvement, curettage is still the preferred treatment. Chemotherapy is not necessary for benign lesions, and amputation is too aggressive. Cementation, phenol, and cryosurgery (liquid nitrogen) are all acceptable local adjuvants to curettage. Packing the cavity with bone graft rather than cement is also acceptable.
An 18-year-old boy has had pain in the right knee for the past 6 months. Examination reveals some fullness behind the knee but no significant palpable soft-tissue mass. There is no effusion, and he has full knee range of motion. The remainder of the examination is unremarkable. A radiograph and MRI scans and biopsy specimens are shown. What is the most likely diagnosis?
1: Parosteal osteosarcoma
2: Classic osteogenic sarcoma
3: Ewing sarcoma
4: Osteochondroma
5: Chondrosarcoma
1: Parosteal osteosarcoma
The patient has parosteal osteosarcoma. The posterior aspect of the distal femur is the typical location for this variant of osteogenic sarcoma. The imaging studies indicate a surface lesion with no involvement of the adjacent intramedullary canal. The histologic appearance is that of a low-grade fibroblastic osteosarcoma, consisting of relatively mature bone and a bland fibroblastic stroma lacking cytologic atypia and mitotic activity. A cartilaginous component is also frequently seen. Classic osteosarcoma typically has a more aggressive radiologic and histologic appearance. Sessile osteochondromas, while common behind the knee, have a presence of hematopoietic marrow and fat. The cartilage found in the associated cartilaginous cap is oriented. Chondrosarcomas are more typical in an older age group and have a histologic pattern consisting of malignant chondroid.
