Accessory spleen originating from the intrinsic muscularis of the stomach misdiagnosed as gastrointestinal stromal tumor: a case report

A 34-year-old man presented to our hospital with a 2-month history of repeated dull upper abdominal pain. Gastroscopy and endoscopic ultrasonography indicated a hemispherical mass at the junction of the greater curvature and the gastric fundus, with hypoechogenicity originating from the intrinsic muscular layer. He was diagnosed with a gastric body submucosal lesion and gastrointestinal stromal tumor, and underwent endoscopic full-thickness resection. However, postoperative pathological examination of the mass unexpectedly revealed heterotopic spleen tissue (accessory spleen). Intragastric ectopic spleen tissue originating from the intrinsic muscular layer of the stomach is a rare clinical condition, with no specific clinical symptoms. This finding is of great clinical significance for the identification of gastric submucosal tumors.