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Presented byGeorge Netto, M.D. and prepared by Andrea Subhawong, M.D.
Case 3: An 18 year old male presented with back pain and muscular weakness in left lower extremity.
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1. Question
Week 392: Case 3
An 18 year old male presented with back pain and muscular weakness in left lower extremity. An epidural L5-S1 mass was evident on MRI studies. A biopsy was performed.images/5.12.09.04a.jpg
images/5.12.09.04b.jpg
images/5.12.09.04c.jpgCorrect
Answer: PNET/Ewing sarcoma
Histology: The tumor is composed of monotonous sheets of small round “blue” cells. The cells contain round nuclei with fine chromatin and scant clear to slightly eosinophilc cytoplasm. Mitotic figures are identifiable. Immunostains for 013, CD117, and synaptophysin were positive. Chromogranin and all other tested markers including cytokeratins, CD45, OCT-4, S100 and GFAP were negative.
Discussion: Ewing sarcoma/PNET is a relatively uncommon tumor. Majority of patients are younger than 20 years. Occasional PNET lesions may demonstrate spindle cell morphology while others can contain larger cells with prominent nuclei. Homer-Wright rosettes are occasionally encountered.
A characteristic t(11;22) (q24;q12) leading to EWS-FLI1 fusion is encountered in 85% of Ewing Sarcoma/PNET cases. The majority of remaining cases (10-15%) demonstrate fusion of the EWS gene with a second member of the ETS family of genes, namely ERG. The EWS-ERG fusion occurs as a result of chromosomal translocation t(21;22)(q22;q12). Chimeric EWS/ETS proteins function as aberrant transcription factors that in turn modulate expression of downstream targets. In current practice, molecular diagnostic techniques are primarily used to confirm the diagnosis of Ewing Sarcoma/PNET and include interphase FISH and RT-PCR mRNA analyses. Other potential applications of molecular diagnostics include monitoring of minimal residual disease and possible role in disease prognostication based on diversity of exonal fusion partners in different cases of Ewing sarcoma/PNET.
Reference(s):
– Ladanyi M. EWS-FLI1 and Ewing’s sarcoma: recent molecular data and new insights. Cancer Biol Ther. 2002 Jul-Aug;1(4):330-336.
– Sandberg AA, Bridge JA. Updates on cytogenetics and molecular genetics of bone and soft tissue tumors: Ewing sarcoma and peripheral primitive neuroectodermal tumors. Cancer Genet Cytogenet. 2000 Nov;123(1):1-26.
– Ginsberg JP, de Alava E, Ladanyi M, Wexler LH, Kovar H, Paulussen M, Zoubek A, Dockhorn-Dworniczak B, Juergens H, Wunder JS, Andrulis IL, Malik R, Sorensen PH, Womer RB, Barr FG. EWS-FLI1 and EWS-ERG gene fusions are associated with similar clinical phenotypes in Ewing’s sarcoma.J Clin Oncol. 1999 Jun; 17(6):1809-1814.Incorrect
Answer: PNET/Ewing sarcoma
Histology: The tumor is composed of monotonous sheets of small round “blue” cells. The cells contain round nuclei with fine chromatin and scant clear to slightly eosinophilc cytoplasm. Mitotic figures are identifiable. Immunostains for 013, CD117, and synaptophysin were positive. Chromogranin and all other tested markers including cytokeratins, CD45, OCT-4, S100 and GFAP were negative.
Discussion: Ewing sarcoma/PNET is a relatively uncommon tumor. Majority of patients are younger than 20 years. Occasional PNET lesions may demonstrate spindle cell morphology while others can contain larger cells with prominent nuclei. Homer-Wright rosettes are occasionally encountered.
A characteristic t(11;22) (q24;q12) leading to EWS-FLI1 fusion is encountered in 85% of Ewing Sarcoma/PNET cases. The majority of remaining cases (10-15%) demonstrate fusion of the EWS gene with a second member of the ETS family of genes, namely ERG. The EWS-ERG fusion occurs as a result of chromosomal translocation t(21;22)(q22;q12). Chimeric EWS/ETS proteins function as aberrant transcription factors that in turn modulate expression of downstream targets. In current practice, molecular diagnostic techniques are primarily used to confirm the diagnosis of Ewing Sarcoma/PNET and include interphase FISH and RT-PCR mRNA analyses. Other potential applications of molecular diagnostics include monitoring of minimal residual disease and possible role in disease prognostication based on diversity of exonal fusion partners in different cases of Ewing sarcoma/PNET.
Reference(s):
– Ladanyi M. EWS-FLI1 and Ewing’s sarcoma: recent molecular data and new insights. Cancer Biol Ther. 2002 Jul-Aug;1(4):330-336.
– Sandberg AA, Bridge JA. Updates on cytogenetics and molecular genetics of bone and soft tissue tumors: Ewing sarcoma and peripheral primitive neuroectodermal tumors. Cancer Genet Cytogenet. 2000 Nov;123(1):1-26.
– Ginsberg JP, de Alava E, Ladanyi M, Wexler LH, Kovar H, Paulussen M, Zoubek A, Dockhorn-Dworniczak B, Juergens H, Wunder JS, Andrulis IL, Malik R, Sorensen PH, Womer RB, Barr FG. EWS-FLI1 and EWS-ERG gene fusions are associated with similar clinical phenotypes in Ewing’s sarcoma.J Clin Oncol. 1999 Jun; 17(6):1809-1814.
