Gastric Schwannoma With Regional Lymphadenopathy

A 64-year-old woman was referred to our hospital because of a gradually enlarged submucosal tumor (SMT), which was followed to that point by a local medical doctor. Laboratory investigations, including serum carcinoembryonic antigen and cancer antigen 19-9 analyses, showed no significant abnormalities. Esophagogastroduodenoscopy revealed an irregular elevated lesion in the top of a SMT in the middle third of the stomach (Figure A), which was confirmed as the mass located predominantly within the muscularis propria and the submucosa by endoscopic ultrasonography (Figure B, arrows). Biopsy analysis of the lesion showed mild chronic changes consistent with gastritis and granulation tissue with nonspecific infiltration of inflammatory cells, but no evidence of malignancy. Abdominal contrast-enhanced computed tomography revealed a well-defined mass with homogeneous enhancement of approximately 6.0 cm in diameter in the middle part of the stomach (Figure C, arrow). It also revealed lymphadenopathy in the perigastric area, with a maximum size of 18 mm (Figure D, arrow). Barium meal examination showed irregular deformity of the gastric wall that projected into the lumen causing smooth indentation in the greater curvature side of the middle third of stomach (Figure E, arrows). The patient underwent distal gastrectomy with reginal lymphadenectomy followed by Billroth I reconstruction. Macroscopic examination of the resected specimen confirmed a protruding mass lesion within the SMT measuring 6.0 cm × 4.2 cm (Figure F, arrows). Microscopic examination of the specimen showed a spindle cell tumor made of broad bundles, interlacing fascicles, and microtrabecular pattern proliferation without mitosis, cellular atypia, or lymph node metastasis (Figure G, arrows). The spindle cells were strongly positive for S100, but negative for c-kit, desmin, and CD34 (Figure H). The postoperative course was uneventful, and the patient has been well without evidence of recurrence for 7 years following the operation. Schwannoma rarely occurs in the gastrointestinal tract, representing 3% of all gastrointestinal mesenchymal tumors and only 0.2% of all gastric tumors.1Kinsey-Trotman S. Balalis G. Gupta A. et al.Gastric schwannoma.J Gastrointest Surg. 2016; 20: 1666-1668Google Scholar, 2Voltaggio L. Murray R. Lasota J. et al.Gastric schwannoma: a clinicopathologic study of 51 cases and critical review of the literature.Hum Pathol. 2012; 43: 650-659Google Scholar The differential diagnosis of SMT includes polypoid tumors arising in the gastric wall, malignant lymphoma, neuroendocrine tumor, and adenocarcinoma. Lymphadenopathy is a helpful distinguishing feature for malignant lymphoma and adenocarcinoma because homogeneous lymph nodes usually accompany the reginal lymph nodes of the stomach.3Namikawa T. Munekage E. Munekage M. et al.Synchronous large gastrointestinal stromal tumor and adenocarcinoma in the stomach treated with imatinib mesylate followed by total gastrectomy.Anticancer Res. 2016; 36: 1855-1859Google Scholar In the present case, lymphadenopathy may reflect reactive lymphoid proliferation similar to the peritumoral lymphoid cuff formation, which was defined as a dense lymphocyte aggregation surrounding the tumor periphery with or without germinal centers. Although lymphadenopathy is suggestive of malignant involvement, a detailed interpretation of computed tomography findings could also provide the necessary clue for diagnosing gastric schwannoma. In addition, endoscopic ultrasonography–guided fine-needle aspiration might play an important role in the diagnosis and management of these patients. Further studies with a larger number of cases are needed to understand the various presentations of this entity.