Switch/Sucrose Non-Fermentable Complex-Deficient Rhabdoid Carcinoma of Stomach: A Rare Case Report and Literature Review.

Gastric undifferentiated/rhabdoid carcinoma is a rare highly invasive tumor of epithelial origin. Due to mutations in the switch/sucrose non-fermentable (SWI/SNF) complex, these tumor cells are usually dedifferentiated, presenting a characteristic rhabdoid profile. In this report, we present a gastric rhabdoid carcinoma in a 77-year-old man who presented with intermittent epigastric pain. Gastroscopy revealed a giant ulcer in the antrum, which proved to be a malignant tumor in the biopsy. Therefore, he was admitted to our hospital and underwent laparoscopic radical gastrectomy and D2 lymphadenectomy. The resected neoplasm contained a variety of rhabdoid cells that lacked well-differentiated elements. Immunohistochemical staining revealed that SMARCA4/BRG1 expression was absent in tumor cells. Finally, the patient was diagnosed with undifferentiated/rhabdoid carcinoma of the stomach. The patient was treated with tegafur-gimeracil-oteracil potassium capsules postoperatively. There were no signs of imaging changes observed at the 18-month follow-up. We reviewed similar cases in previous reports. These tumors are more likely to affect older male adults and usually lack typical symptoms. Histologically, most tumor cells are poorly cohesive and rhabdoid, and differentiated compositions of various degrees can occasionally be seen. Positive staining for vimentin was seen in all tumor cells. Epithelial markers are positive in the majority of tumors. SWI/SNF mutant tumors tend to be associated with a poor prognosis. In this review, more than half of the patients died within one year after surgery. The treatments for these diseases are still being explored.