Practice questions answers bone tumors

Practice questions answers

Bone tumors

© Jun Wang, MD, PhD

1. C. Key diagnostic features of osteoid osteoma include small size, clear margin and benign bone formation. Aneurysmal bone cyst is composed of non-endothelial lined blood filling space. Osteoblastoma has microscopic features identical to osteoid osteoma, but it is different in clinical presentations, size, bone involved, etc. Osteomyelitis has inflammation and bone necrosis. Osteosarcomas are malignant tumor with bone production. Microscopically they are pleomorphic malignant cells. Radiologically they have destruction appearance.

2. D. Osteoblastoma has microscopic features identical to osteoid osteoma, but it is different in clinical presentations, size, bone involved, etc. Ewing sarcomas are composed of sheets of small cells with round nuclei. Giant cell tumors have numerous multinucleated cells. Metastatic cancers have epithelial components similar to primary tumors. Osteosarcomas are malignant tumor with bone production. Microscopically they are pleomorphic malignant cells. Radiologically they have destruction appearance.

3. E. Malignant tumor producing osteoid is osteosarcomas. Chondrosarcoma produces cartilage, but not bone. Osteoblastoma has bone formation from benign cells, and radiologically it usually has clear margins. No pleomorphic tumor cells should be seen in osteomyelitis.

4. D. Multicentric Osteosarcomas commonly harbor p53 mutation. Abnormality of EX1 is seen in multiple hereditary exostoses. EWS abnormality is seen in Ewing sarcomas. IDH1 abnormality is seen in enchondroma. SYT abnormality is seen synovial sarcoma.

5. E. Malignant tumor producing osteoid is osteosarcomas. Diffuse large B cell lymphoma would not produce bone. Chondrosarcoma produces cartilage, but not bone. Ewing sarcomas are composed of sheets of small cells with round nuclei. Osteoblastoma has bone formation from benign cells, and radiologically it usually has clear margins. Codman’s triangle can be seen in osteosarcomas and Ewing sarcomas, but not in benign bone tumors.

6. D. Almost morphologically normal bone growth with benign cartilage cap is most likely osteochondroma. Chondromas are benign cartilage producing tumor. Chondrosarcoma produces cartilage, but not bone. Ewing sarcomas are composed of sheets of small cells with round nuclei. Osteosarcomas are bone producing malignant tumor with pleomorphic tumor cells.

7. A. This is most likely a case of multiple hereditary exostoses, commonly associated with abnormality of EX1 or EX2. EWS abnormality is seen in Ewing sarcomas. HMGA2 abnormality is seen in chondroma. RB abnormality is common in osteosarcomas. SYT abnormality is seen synovial sarcoma.

8. B. Cartilage producing tumor with pushing border is most likely a benign chondroma, and in this case, provided the clinical presentations, is most likely enchondroma. Chondrosarcoma has infiltrating border and commonly entrap normal bone trabeculae. Osteochondroma usually presents with a pedunculated outgrown with morphologically unremarkable bone stem and cartilage cap. Osteoid osteoma has benign bone formation. Osteosarcomas are bone producing malignant tumor with pleomorphic tumor cells.

9. D. IDH1 abnormality is seen in enchondroma. EWS and FLI1 fusion is seen in Ewing sarcomas. EX1 or EX2 abnormality is seen in multiple hereditary exostoses. RB abnormality is common in osteosarcomas.

10. B. Cartilage producing tumor with an invasive border is most likely chondrosarcoma. Chondromas are benign cartilage producing tumor without invasion. Osteoblastoma has bone formation from benign cells, and radiologically it usually has clear margins. Osteochondroma usually presents with a pedunculated outgrown with morphologically unremarkable bone stem and cartilage cap. Osteosarcomas are bone producing malignant tumor with pleomorphic tumor cells.

11. D. Lytic lesions caused by abnormal activity of bone absorption, without invasive borders, and contains numerous multinucleated giant cells are most likely giant cell tumors of bone. Aneurysmal bone cyst is characterized by non-endothelial lined blood filling space. Tuberculosis usually has more sever chronic granulomatous inflammation and necrosis. Burkitt lymphoma usually has sheets of small to intermediate sized round B cells with brisk mitosis and numerous tingible body macrophages.

12. E. The real neoplastic cells in giant cell tumors of bone are the mononucleated cells that produce RANKL. Production of RANKL is a critical step in recruiting monocytes to form those giant cells. CD3 is a T cell marker, CD20 is a B cell marker. Cyclin D1 overexpression is usually seen in mantle cell lymphoma. OPG (osteoprtegerin, AKA osteoclastogenesis inhibitory factor) is produced by osteoblasts in bone that will inhibit bone absorption.

13. A. Radiolucent lesion with well-defined borders, blood-filled cysts without endothelial lining is most consistent with aneurysmal bone cyst. Giant cell tumor is usually solid with numerous multinucleated cells. Fibrous dysplasia has disorganized poorly developed bone trabeculae. Nonossifying fibroma has solid fibrous background with scattered osteoclasts but without bone formation. Osteosarcomas are bone producing malignant tumor with pleomorphic tumor cells.

14. B. Sheets of small round cells with CD99 expression is highly suggestive of Ewing sarcomas. Burkitt lymphoma and T-cell acute lymphoblastic leukemia/lymphoma are positive for CD45. Hodgkin lymphoma contains Reed-Sternberg cells. Osteosarcomas are bone producing malignant tumor with pleomorphic tumor cells. They are usually negative for CD99.

15. E. CD99 is positive in Ewing sarcomas. CD3 is positive in T cells, CD20 is positive in B cells. CD10 can be positive in various lymphomas, including diffuse large B cell lymphoma, follicular lymphoma, and Burkitt lymphoma. CD30 is positive in Reed-Sternberg cells of Hodgkin lymphoma, as well as anaplastic large-cell lymphoma.

16. D. T(2;8) involving PAX3 is seen in embryonal rhabdomyosarcoma. t(8;14) involving c-myc and IgH can be seen in Burkitt lymphoma. t(9;22) involving ABL is seen in chronic myelogenous leukemia. t(X;18) involving SYT is seen in synovial sarcoma.

17. D. Solid tumor with numerous multinucleated giant cells adjacent to tendon is most likely giant cell tumor of tendon sheath. The history is suggestive of a foreign body reaction, a condition usually has granulomatous changes. Ganglion cyst is a mucin containing cyst without epithelial lining. Giant cell tumors of bone arise within the bone. Superficial fibromatosis is characterized by blunt fibroblast proliferation that may affect tendon functions. It usually does not have giant cells.

18. D. Radiolucent lesion with well-defined border, fibrotic background without bone formation is consistent with fibrous cortical defect/non-ossifying fibroma, depending on size of the lesion. Fibrosarcomas are hypercellular lesion with hyperchromic nuclei forming a herringbone pattern. Fibrous dysplasia has disorganized poorly developed bone trabeculae. Giant cell tumors of bone have numerous multinucleated giant cells. Primary myelofibrosis is a type of myeloproliferative neoplasms that is characterized by anemia with teardrop-shaped red cells, splenomegaly and usually seen in middle age and older adults.

19. C. Burkitt lymphoma usually has sheets of small to intermediate sized round B cells with brisk mitosis and numerous tingible body macrophages. Fibrous cortical defect/non-ossifying fibroma does not have bone formation. Osteosarcomas are bone producing malignant tumor with pleomorphic tumor cells. Primary myelofibrosis is a type of myeloproliferative neoplasms that is characterized by anemia with teardrop-shaped red cells, splenomegaly and usually seen in middle age and older adults.

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