Gastric Flat Elevated Undifferentiated Signet-ring Cell Mucosal Cancer Lesion Detected in a Case without Helicobacter pylori Infection.

Protruded signet-ring cell carcinoma (SRCC) is extremely rare. We herein report a rare case of flat elevated gastric SRCC in a patient without Helicobacter pylori infection. Esophagogastroduodenoscopy of a woman in her 50s revealed a flat, whitish lesion in the gastric body with elevation. Histological results of an endoscopically biopsied specimen led to a diagnosis of SRCC. Resection using endoscopic submucosal dissection was performed, and histology results revealed that the tumor was localized in the lamina propria. The size was 10×6 mm, and a protrusion had been formed by SRCC enlargement without destruction of the surface epithelium structure.