SMARCA4 and gastric neuroendocrine tumor, well differentiated, low or intermediate grade: To our knowledge, we describe for the first time, an extremely rare case of synchronous GNET and SMARCA4-deficient undifferentiated carcinoma with independent origins in the small intestine.<h4>Case presentation</h4>A 46-year-old woman presented with multiple small intestine masses and underwent surgical resection.