Yonsei Med J 49(6):1052 - 1054, 2008 DOI 10.3349/ymj.2008.49.6.1052 Gastric Schwannoma Ho Young Yoon,1 Choong Bai Kim,1 Yoon Hee Lee,2 and Ho Guen Kim2 Departments of 1Surgery and 2Pathology, Yonsei University College of Medicine, Seoul, Korea. Schwannomas, also known as neurinomas or neurilem- momas, are generally benign, slow-growing neoplasms origi- nating in any nerve that has a Schwann cell sheath. These neoplasms are rare among the spindle cell mesenchymal tumors of the gastrointestinal tract, but develop most commonly in the stomach representing 0.2% of all gastric tumors. We present the case of a 57-year-old female patient with a large schwannoma in the stomach that was palpable in the abdomen. She under- went subtotal gastrectomy under suspicion of gastrointestinal stromal tumor (GIST), but post-operative histopathological and immunohistochemical findings showed a fascicular arrange- ment of spindle cell with pallisading nuclei, and positive for S-100 protein with negative smooth muscle actin (SMA). These results confirmed schwannoma as the diagnosis. Key Words: Schwannoma, stomach, submucosal tumor, S-100 protein INTRODUCTION Schwannomas also known as neurinomas or neurilemmomas, are tumors originating from any nerve that has a Schwann cell sheath. These rarely develop in the gastrointestinal tract, and the most common site along the GI tract is the stomach. Schwannomas make-up 0.2% of all gastric neo- plasm.1 The tumors are usually benign, slow-gro- wing, and asymptomatic, but in some cases, bleeding or a palpable mass is present. Gastroin- testinal endoscopy is the principal diagnostic tool. However, when the tumor has the characteristics of an exophytic mass from the gastric wall to the abdominal cavity, the differentiation of a schwan- noma from other submucosal tumors is very dif- Received June 12, 2007 Accepted July 4, 2007 Reprint address: requests to Dr. Choong Bai Kim, Department of surgery, Yonsei University College of Medicine, 250 Seongsanno, Seodaemun-gu, Seoul 120-752, Korea. Tel: 82-2-2228-2113, Fax: 82-2-313-8289, E-mail: cbkimmd@yuhs.ac Yonsei Med J Vol. 49, No. 6, 2008 ficult on pre-operative examination. The diagno- stic determination of schwannomas requires his- tological testing to be positive for the S-100 pro- tein and vimentin but negative for both smooth muscle actin and c-KIT. Because most schwan- nomas have an excellent prognosis, surgical removal is sufficient for treatment. Here we present a 57-year-old woman with a gastric schwannoma manifesting as a palpable mass in the abdomen, which was confirmed pathologi- cally after surgery. CASE REPORT A 57-year-old woman with diabetic nephropathy, hypertension, and angina was referred to our institution for an incidentally-detected abdominal mass detected by sonography. She did not have any other clinical complaints. Physical examination revealed a palpated golf ball-sized mass in the epigastric area without tenderness or rebound tenderness. Gastrointestinal endoscopy was not performed due to her medical history of angina. Instead, an upper gastrointestinal barium study showed a large submucosal mass in the gastric angle (Fig. 1). Computed tomography of the abdomen revealed an ovoid and homogenous 7 × 5 × 4 cm soft tissue mass at the lesser curvature in the lower body of the stomach (Fig. 2). Aside from splenomegaly, there was no evidence of metastasis. To facilitate visualization of the mass, we performed a sono- graphy, which depicted an ill-defined round mass neighboring the antrum. The mass was approxi- mately 6 × 5 × 4 cm in diameter and had a homo- genous internal echo (Fig. 3).