Practice questions answers soft tissue tumors

Practice questions answers

Soft tissue tumors

©Jun Wang, MD, PhD

1. A. Lipoma is histologically identical to normal adipose tissue, with the exception of either grossly or microscopically identified fine fibrous capsule. Both myxoid liposarcoma and well differentiated liposarcoma will have lipoblasts, cells with multiple intracellular vacuoles and enlarged irregular hyperchromic nuclei. Recurrently carcinomas have features of previous carcinomas, either atypical squamous cells with intercellular bridges or keratin pearl for squamous cell carcinoma, or irregular glands for adenocarcinoma.

2. E. Presence of adipose tissue is highly suggestive of adipose tissue differentiation. Well differentiated liposarcoma is characterized by mature adipose tissue containing lipoblasts. All adipose tissue is positive for S-100. Mucinous carcinomas are positive for cytokeratin, and usually have recognizable mucin-producing epithelial cells. Melanomas can mimic anything, but they are positive for both S-100 and HMB45. Metastasis of leiomyoma has been reported, but leiomyomas are usually spindle cells that are negative for S-100.

3. D. Rod/Ring chromosome involving 12q is seen in well differentiated liposarcoma. T(12;16) involving FUS-DDIT3 is seen in myxoid liposarcoma. Beta-catenin mutation is seen in
ovarian endometrioid adenocarcinoma, stomach cancer, colon adenoma, solid-pseudopapillary neoplasm and pilomatricoma. BRAF mutation can be seen many neoplasms, including melanocytic nevi, melanoma, hairy cell leukemia, etc. t(X;18) is seen in synovial sarcoma.

4. A. Dedifferentiated liposarcoma is defined as a tumor containing abrupt transformation from a low grade sarcoma, commonly well differentiated liposarcoma. Diffuse large B cell lymphoma is positive for CD45. All carcinomas are positive for cytokeratin. Myxoid liposarcoma have either myxoid background or round poorly differentiated tumor cells.

5. E. Although Burkitt lymphomas are characterized by intermediate sized round tumor cells with numerous mitosis, they are positive for CD45. Diffuse large B cell lymphoma is also positive for CD45. Ewing sarcoma is positive for CD99, all three of these are negative for S-100.

6. T(12;16) involving FUS-DDIT3 is seen in myxoid liposarcoma. T(2;8) involving PAX3 is seen in embryonal rhabdomyosarcoma. T(11,22) involving EWS is seen in ewing sarcoma. T(17;22) involving MYH9 is seen in nodular fasciitis. T(X;18) involving SYT is seen in synovial sarcoma.

7. D. Markedly pleomorphic tumor with scattered lipoblasts is most compatible with pleomorphic liposarcoma, provided no myxoid/round cell liposarcoma or well differentiated liposarcoma components are identified. Diffuse large B cell lymphoma is positive for CD45. All carcinomas are positive for cytokeratin. Malignant peripheral nerve sheath tumor is usually spindle cell tumor without adipose tissue differentiation. Undifferentiated pleomorphic sarcoma is a diagnosis of exclusion, commonly used when only vimentin is positive in a markedly pleomorphic high-grade tumor, or immunohistochemistry results are inconclusive.

8. D. Nodular fasciitis is characterized by a rapid growing mass with history of trauma. It usually has a myxoid background with scattered spindle cells and stellate cells, as well variable inflammatory cells. Hematoma is a result of local hemorrhage and should have signs such as hemosiderin-laden macrophages, or old blood. Hodgkin lymphoma has Reed Sternberg cells or popcorn cells. Myxoid liposarcoma will have lipoblasts. Synovial sarcoma usually presents with spindle cell proliferation with or without glandular components.

9. E. Superficial fibromatosis is characterized by blunt fibroblast proliferation that may affect tendon functions. Microscopically they are similar to dense connective tissue, except with mild hypercellularity. Fibrosarcomas are hypercellular with a herringbone pattern. Leiomyoma and leiomyosarcoma are usually spindle cell proliferation with positive reactivity to desmin, while pleomorphism, active mitosis and necrosis are expected to be seen in the latter. Malignant peripheral nerve sheath tumors are spindle cell tumors positive for S-100.

10. A. This is most likely Gardner syndrome, an autosomal dominant disorder with familial adenomatous polyposis, osteomas and deep fibromatosis. Fibrosarcomas are hypercellular with a herringbone pattern. Leiomyoma and leiomyosarcoma are usually spindle cell proliferation with positive reactivity to desmin, while pleomorphism, active mitosis and necrosis are expected to be seen in the latter. Familial adenomatous polyposis has markedly increased risk of colon cancer, but all carcinomas are positive for cytokeratin. 

11. A. Gardner syndrome is a type of familial adenomatous polyposis, due to mutations of either APC or beta-catenin. NF1 mutation is associated with neurofibromatosis 1, commonly associated with neurofibroma, schwannoma, and malignant peripheral nerve sheath tumor. N-myc mutation is seen in alveolar rhabdomyosarcoma. PAX3 abnormality is seen in embryonal rhabdomyosarcoma. SYT abnormality is seen in synovial sarcoma.

12. A. Li-Fraumeni syndrome is associated with p53 mutation and various malignancies. Maffucci syndrome is characterized by multiple enchondromas, hemangioma (subcutaneous), and soft tissue lymphangiomas. Neurofibromatosis is associated with neurofibroma, schwannoma, and malignant peripheral nerve sheath tumor, usually due to mutation of NF1 or NF2. Tuberous sclerosis is characterized hamartomatous involving brain, eyes, heart, etc, associated with TSC1 or TSC2 mutations.

13. B. Angiosarcoma can occur after surgery and radiation therapy of breast cancers, but microscopically it is composed of anastomosing vessels lined by atypical endothelial cells, that express CD34. Leiomyosarcomas are usually pleomorphic spindle cell proliferation with positive reactivity to desmin. Malignant peripheral nerve sheath tumors are spindle cell tumors positive for S-100. Recurrent ductal carcinomas have irregular glandular growth with infiltrating pattern and express cytokeratin.

14. B. This tumor contains rhabdomyoblast that is confirmed by positive desmin reactivity. Burkitt lymphomas are positive for CD45. Leiomyosarcomas are usually pleomorphic spindle cell proliferation, and should not have rhabdomyoblast. Small cell carcinoma are characterized by packed molding small cells with scant cytoplasm and salt and pepper pattern chromatin. Synovial sarcoma usually presents with spindle cell proliferation with or without glandular components. Both are positive for cytokeratin.

15. See answer to question 11.

16. C. This is most likely a botryoid rhabdomyosarcoma. CD38 is a plasma cell marker. It is positive in neoplasm with plasma cell differentiation, including plasmacytoma, multiple myeloma, and lymphoplasmacytic lymphoma. Chromogranin is a marker for neuroendocrine tumors, including carcinoid and small cell carcinoma. EMA is positive in epithelial cells and synovial sarcoma. P16 is commonly positive for HPV associated neoplasms.

17. B. The alveolar pattern of growth, presence of multinucleated rhabdomyoblast and positive reactivity to desmin are most compatible with alveolar rhabdomyosarcoma. Adult T-cell leukemia/lymphoma, Hodgkin lymphoma, and small lymphocytic lymphoma are positive for CD45, or negative for desmin. Small cell carcinoma are characterized by packed molding small cells with scant cytoplasm and salt and pepper pattern chromatin. It is positive for cytokeratin.

18. D. EGFR mutation is seen in various cancers, including adenocarcinoma of lung. See answer to question 11 also.

19. D. Location, morphology and desmin reactivity are consistent with leiomyosarcomas. Endometrial stroma sarcomas usually have relatively monotonous cells. Leiomyoma may have bizarre nuclei but should not have numerous mitosis. Malignant mixed mullerian tumor is characterized by containing both malignant epithelial (cytokeratin positive) and stromal components (vimentin positive).

20. E. This is a tumor with EMA positive spindle cells, a feature consistent with synovial sarcoma, monophasic type. Ewing sarcoma may occur in soft tissue. It is usually sheets of CD99 positive small cells with round nuclei. Nodular fasciitis is characterized by a rapid growing mass with history of trauma. It usually has a myxoid background with scattered spindle cells and stellate cells, as well variable inflammatory cells. Ostersarcoma is by definition a bone producing malignant tumor. Rhabdomyosarcomas are positive for desmin.

21. E. EWS abnormality is seen in ewing sarcoma. FUS abnormality is seen in myxoid liposarcoma. MDM is seen in well differentiated liposarcoma. MYH9 abnormality is seen in nodular fasciitis.

22. D. This is a case of malignant peripheral nerve sheath tumor in the background of neurofibromatosis 1. CD30 is positive for classic Hodgkin lymphoma and anaplastic large-cell lymphoma. Desmin is positive for muscular tissue. EMA is positive in epithelial tissue and synovial sarcoma. von Willebrand's factor is usually expressed in endothelial tissue, including angiosarcoma.

23. C. NF1 is associated with neurofibromatosis 1. Beta-catenin mutation can be seen in Gardner syndrome. FUS abnormality is seen in myxoid liposarcoma. N-myc mutation is seen in alveolar rhabdomyosarcoma. SYT abnormality is seen in synovial sarcoma.

24. E. T cell and B cell lymphomas are usually CD45 positive. Synovial sarcoma and carcinomas usually express cytokeratin.

Back to practice questions soft tissue tumors

Back to soft tissue tumors

Back to contents