Abstract
A 16-year old female presented with a pre-syncopal event and one episode of melena. Her stool was positive for occult blood and her hemoglobin was 6.1g/dl. A mass in the greater curvature of the stomach was noted on endoscopy, and endoscopic ultrasound confirmed the presence of a heterogeneous gastric mass arising from the submucosa. Laparoscopic visualization followed by partial gastrectomy and biopsies revealed a 7.5 cm centrally-ulcerated antral mass arising from the muscularis with multiple areas of ischemic necrosis and hyalinization. Focal nuclear enlargement and hyperchromasia were also noted. Immunohistochemically, the tumor was negative for CD117, CD34 and desmin, but positive for S-100, consistent with the diagnosis of Schwannoma. Schwannomas are rare gastrointestinal mesenchymal tumors that occur most commonly in the stomach as a nodular mass in the muscularis propria. As such, they are sometimes misdiagnosed as neurofibromas and Gastrointestinal Stromal Tumors. Histologically, they have prominent peripheral lymphocytic aggregates with or without a germinal center. They are mainly composed of spindle cells, but epithelioid and rare plexiform variants have also been described. Immunohistochemically, they stain positive for vimentin and S-100 protein, but negative for CD117. Gastrointestinal Schwannomas are benign tumors and have a good prognosis even when treated with enucleation.
Keywords: Schwannoma, gastric mesenchymal tumors, S-100 immunostaining, upper gastrointestinal bleeding
Related Books
Common Pediatric Diseases: an Updated Review
19