[Gastric schwannoma: rare differenzial diagnosis of acute upper gastrointestinal (GI) bleeding]. / Schwannom des Magens: seltene Differenzialdiagnose einer akuten oberen gastrointestinalen Blutung.

Schwannomas are benign tumors derived from Schwann cells and their typical site of origin is the subcutaneous tissue of the extremities. Gastrointestinal localization of Schwannomas is extremely rare and the stomach is the prevalent site. Gastric schwannomas primarily occur in the gastric submucosa and are usually asymptomatic.We present a rare case of a solitary gastric schwannoma in a 51-year old male, which initially manifested with hematemesis by acute upper gastrointestinal (GI) bleeding. The upper GI-Endoscopy revealed a gastric submucosal tumor, 7 cm in size, located in the proximal corpus and fundus. In the endoscopical Ultrasound (EUS-Examination), the lesion appeared to arise from the fourth proper muscle layer (Muscularis propria). The fourth layer origin and the isoechogenicity, as compared to the normal muscle layer, are endoscopic ultrasonographic characteristics of gastric schwannomas and help in distinguishing them from gastrointestinal tumors (GIST). Because of the unclear histological identity, the patient underwent a "rendezvous" endoscopic-laparoscopic surgical resection of the tumor in toto. The histomorphological features of the lesion and the strong expression of S100 in combination with absence of DOG1 expression indicated the diagnosis of gastric schwannoma. There was no evidence of malignancy. The postoperative course was uncomplicated.This is a very rare manifestation of gastric schwannoma, representing a rare differenzial diagnosis in a case of acute upper GI-Bleeding. Only 14 % of gastric schwanommas are presented with gastrointestinal bleeding, including mainly melena rather than hematemesis. This case is considered to be worthy of presentation owing to the rare and unusual cause of upper GI bleeding implied in it.