Quiz-summary
0 of 1 questions completed
Questions:
- 1
Information
Presented by Theresa Chan, M.D. and prepared by Ali Ansari-Lari, M.D.,Ph.D.
Case 6: 14 year old male with a pelvic mass.
You have already completed the quiz before. Hence you can not start it again.
Quiz is loading...
You must sign in or sign up to start the quiz.
You have to finish following quiz, to start this quiz:
Results
Time has elapsed
Categories
- Not categorized 0%
- 1
- Answered
- Review
-
Question 1 of 1
1. Question
Week 124: Case 6
14 year old male with a pelvic mass.images/TCH6a.JPG
images/TCH6b.JPG
images/TCH6c.JPG
images/TCH6d.JPG
images/TCH6e.JPGCorrect
Answer: Ewing’s sarcoma/primitive neuroectodermal tumor (PNET)
Histology: This tumor consists of sheets of solidly packed tumor cells with uniformly round or ovoid vesicular nuclei. Nucleoli are small and inconspicuous. The cytoplasm appears cleared-out with vacuoles, which corresponds to intracellular glycogen deposition. Rosettes are not seen.
Discussion: Ewing’s sarcoma/PNET is now recognized as a family of tumors that share a common cytogenetic abnormality. Ewing’s/PNET have the characteristic translocation of the long arm of chromosomes 11 and 22 [t(11;22)(q24;q12)]. Morphologically, these tumors range from the histology seen in this case with sheets of uniform round tumor cells without prominent nucleoli or rosette formation to tumors with irregular shaped nuclei showing prominent nucleoli and Homer Wright or Flexner-Wintersteiner rosettes. The histology seen in the current case would have in the past been classified as a classic Ewing’s sarcoma. Tumors showing more nuclear variation and having rosette formation would have been classified previously as PNET. Ewing’s sarcoma/PNET labels in a membranous fashion for 013 or CD99 (MIC2), may rarely be focally positive for NSE, S-100 and Cytokeratin, and are negative for desmin, myogenin. It is important to be aware that CD99 is not specific for Ewing’s sarcoma/PNET, and can be expressed in lymphoblastic lymphoma, rhabdomyosarcoma and IDSRCT.
The differential diagnosis includes the list of small round blue cell tumors, including IDSRCT, rhabdomyosarcoma, lymphoblastic lymphoma and small cell carcinoma.
IDSRCT is characterized by a nested pattern with prominent desmoplastic stroma, with the tumor nests often showing peripheral palisading with central necrosis. IDSRCT are diffusely positive for cytokeratin, desmin and NSE. Lymphoblastic lymphoma may be ruled out by immunohistochemical staining for LCA. Rhabdomyosarcoma, in contrast to Ewing’s sarcoma/PNET, is strongly positive for desmin and myogenin/myoD1.
Incorrect
Answer: Ewing’s sarcoma/primitive neuroectodermal tumor (PNET)
Histology: This tumor consists of sheets of solidly packed tumor cells with uniformly round or ovoid vesicular nuclei. Nucleoli are small and inconspicuous. The cytoplasm appears cleared-out with vacuoles, which corresponds to intracellular glycogen deposition. Rosettes are not seen.
Discussion: Ewing’s sarcoma/PNET is now recognized as a family of tumors that share a common cytogenetic abnormality. Ewing’s/PNET have the characteristic translocation of the long arm of chromosomes 11 and 22 [t(11;22)(q24;q12)]. Morphologically, these tumors range from the histology seen in this case with sheets of uniform round tumor cells without prominent nucleoli or rosette formation to tumors with irregular shaped nuclei showing prominent nucleoli and Homer Wright or Flexner-Wintersteiner rosettes. The histology seen in the current case would have in the past been classified as a classic Ewing’s sarcoma. Tumors showing more nuclear variation and having rosette formation would have been classified previously as PNET. Ewing’s sarcoma/PNET labels in a membranous fashion for 013 or CD99 (MIC2), may rarely be focally positive for NSE, S-100 and Cytokeratin, and are negative for desmin, myogenin. It is important to be aware that CD99 is not specific for Ewing’s sarcoma/PNET, and can be expressed in lymphoblastic lymphoma, rhabdomyosarcoma and IDSRCT.
The differential diagnosis includes the list of small round blue cell tumors, including IDSRCT, rhabdomyosarcoma, lymphoblastic lymphoma and small cell carcinoma.
IDSRCT is characterized by a nested pattern with prominent desmoplastic stroma, with the tumor nests often showing peripheral palisading with central necrosis. IDSRCT are diffusely positive for cytokeratin, desmin and NSE. Lymphoblastic lymphoma may be ruled out by immunohistochemical staining for LCA. Rhabdomyosarcoma, in contrast to Ewing’s sarcoma/PNET, is strongly positive for desmin and myogenin/myoD1.
