Personalized genomic analysis based on circulating tumor cells of extra-skeletal Ewing sarcoma of the uterus: A case report of a 16-year-old Korean female.

A 16-year-old female with Ewing sarcoma, a very rare disease with poor prognosis in women, was admitted to the hospital with abdominal pain. Diagnostic laparotomy revealed the Ewing sarcoma originating from the extramural uterus. Histological examination yielded positive test results for CD99, vimentin, S-100, eosin 5-maleimide and periodic acid-Shiff. EWS-FLI1 type 1 translocation was confirmed. Fibroblast growth factor receptor (FGFR) 4 (c.1162G> A) and HRas proto-oncogene (HRAS; c.182A> G) mutations were also detected. At eight months following complete remission, pelvic lymph node metastasis was confirmed. Epithelial cell adhesion molecule-positive circulating tumor cells (CTCs) were detected in liquid biopsy. FGFR3 (c.1948A> G) and FGFR4 (c.1162G> A) mutations were found in the CTCs. FGFR4 (c.1162G> A) and HRAS (c.182A> G) mutations were confirmed in cell-free circulating tumor DNA. A sequence of EWSR1 gene was also confirmed in the CTCs. To the best of our knowledge, this is the first report of skeletal Ewing sarcoma being detected using multiple noninvasive diagnostic methods to observe genetic translocation and mutation in blood CTCs. It may be used to monitor the therapeutic effect of cancer or predict prognosis. Therefore, liquid biopsy is expected to serve a pivotal role in ultra-precise medicine in the future.