Ewing's Sarcoma of Stomach Masquerading as Gastric Cancer: A Case Report and Literature Review.

[BACKGROUND] Ewing's sarcomas (ES) are exceedingly malignant undifferentiated small round cell tumors of the neuroectodermal origin. It primarily occurs in the skeletal tissue; however, it has also been documented in extraskeletal tissues, including the small intestine, esophagus, vagina, pancreas, ovaries, rectovaginal septum, prostate, and kidneys.Extraskeletal Ewing sarcoma (EES) constitutes approximately 15-20% of neoplasms within the ES family, which includes both Ewing sarcoma/peripheral neuroectodermal tumors (ES/PNET) and EES. Extraskeletal ES are frequently observed in the paraspinal region, limbs and retro peritoneum. Encountering primary gastric ES is exceptionally rare.

[METHODS AND RESULT] We, herby, present here an extremely rare case of primary gastric ES in a 17-year-old male who had presented to us with features of gastric outlet obstruction. Contrast-enhanced abdominal computed tomography revealed an asymmetrical circumferential thickening of about 5 cm in the antropyloric region of the stomach and the first part of the duodenum, with multiple enlarged perigastric lymph nodes. Endoscopic biopsy revealed a tumor composed of cells arranged in nests, cords and sheets. An extensive immunohistochemistry panel examination found tumor cells to be strongly positive for vimentin, NKX2.2, FLI1, CD99 and CK.The patient received 9 weeks of neoadjuvant chemotherapy based on IE-VAC regimen. The patient underwent elective classical pancreaticoduodenectomy (Whipple's procedure). The postoperative course of the patient unfolded without any complications. The patient was subsequently discharged in a state of good health 12 days post-procedure. Thereafter, he underwent four cycles of adjuvant chemotherapy.

[DISCUSSION] A review of the elucidated cases of primary gastric Ewing's sarcoma depicts its aggressive nature with frequent regional and distant metastasis, and mostly manifesting through non-specific clinical features, thereby, evading early diagnostic efforts. A comprehensive multimodal therapeutic strategy, with chemotherapy, radiotherapy, and surgical intervention is typically employed.We, thus, report this case to help with disease identification and acceptance for the clinicians.

[HOW TO CITE THIS ARTICLE] Pawar SS, Priya S, Kumar M, Ewing's Sarcoma of Stomach Masquerading as Gastric Cancer: A Case Report and Literature Review. Euroasian J Hepato-Gastroenterol 2025;15(1):1-9.