2021 Volume 63 Issue 9 Pages 1616-1622
A 42-year-old man presented to a clinic with a chief complaint of anal pain. Rectal examination and transanal echography revealed the presence of a tumorous lesion. At our hospital, while CT and MRI showed a 65×55mm tumor that had evacuated the lower rectum, colonoscopy revealed that a part of the tumor was exposed at the mucosal surface of the rectum. Even though we performed a forceps biopsy, most of specimen was necrotic and insufficient for pathological diagnosis.
Therefore, colonoscopy was performed followed by EUS-FNA, and the samples obtained for EUS-FNA were adequate for pathological analysis as they contained lesser necrotic tissue. H&E staining revealed a high N/C ratio and proliferation of atypical cells with unclear nucleoli. However, morphological images did not show differentiation to a cancer cell. Immunostaining was positive for NSE and CD99 and partially positive for c-kit, CD4, CD56, and chromogranin. Genetic analysis revealed the presence of the fusion gene EWS/FLI-1, confirming the diagnosis of Ewingʼs sarcoma.
The frequency of extra skeletal pelvic Ewingʼs sarcoma, as seen in our patient, is rather low. Cytogenetic analysis and immunostaining are strongly recommended for the diagnosis of Ewingʼs sarcoma. In such cases, tissue biopsies are mainly performed with CT-guided, open laparotomy and laparoscopic methods. This report is the first to describe the diagnosis of Ewingʼs sarcoma using EUS-FNA. In cases of hypervascular tumors requiring immunohistological and genetic examinations for diagnosis, it is necessary to obtain sufficient sample with lower risk of bleeding. Additionally, EUS-FNA is a potentially safer and more useful method than forceps biopsy.
