Resident Program - Case of the Month

June 2022 – Presented by Dr. Anupam Mitra (Mentored by Dr. Kurt Schaberg)

Reveal

The tumor cells are diffusely positive for membranous CD99 and nuclear FLI-1 or Erg. Most common translocation in Ewing Sarcoma is t(11;22) which is EWSR1-FLI1 fusion (60-65% cases) followed by the next common translocation t(21:22) which is EWSR1-Erg fusion (5-10% cases). There are some rare fusion partners with EWSR1 such as ETV2, ETV4, NFATC2 etc.

Extra-skeletal Ewing Sarcoma of the vulva is relatively rare and till date only a handful of cases has been reported. This commonly affects children and young adults. Morphologically the tumor consists of uniform small round blue cells with or without associated hemorrhage or necrosis. The tumor cells are diffusely positive for membranous CD99 and nuclear FLI-1 or Erg as seen in our case. The diagnosis is confirmed by EWSR1 translocation by FISH study.

This tumor has a propensity to early metastasize to bone and lungs. The 10-year survival is approximately 65% in localized disease vs. 30% in metastatic disease. In our case, the disease is localized to the vulva only, thus the outcome seems to be on the better side. Chemotherapy is the treatment of choice for most cases. Surgical resection of residual tumor and radiation therapy are also done on selected cases. Our patient received chemotherapy and doing well till now.

References

1. https://pubmed.ncbi.nlm.nih.gov/?term=ewing+sarcoma%2C+vulva&size=50
2. https://schaberg.faculty.ucdavis.edu/wp-content/uploads/sites/604/2019/07/SRBCT.pdf
3. https://app.expertpath.com/document/extraskeletal-ewing-sarcoma/c2016b1f-8f4b-4cdc-8344-994d273462b2?searchTerm=Ewing%20Sarcoma