Unusual Presentation of Gastric MALT Lymphoma: A Case of Endoscopic Submucosal Dissection (ESD) Revealing a Localized Lymphoepithelial Lesion

Abstract

Purpose: Case: A 76-year-old woman was referred from a community hospital for poorly differentiated gastric adenocarcinoma. She was otherwise healthy and past medical history was unremarkable. Physical examination at presentation did not show any abdominal mass or palpable lymphadenopathy. Laboratory evaluation was likewise unrevealing. A diagnostic upper endoscopy in our unit revealed a 2-cm raised, submucosal lesion with central erosion in the upper body of the stomach. Repeated biopsies of the lesion were interpreted as inflamed gastric mucosa with positive H. pylori. Systematic gastric biopsies to rule out any foci of mucosa associated lymphoid tissue (MALT) lymphoma (MALToma) changes were negative. CT of chest and abdomen was negative for any lymphadenopathy or distant metastases. Based on the endoscopic findings and repeated negative biopsy results, we performed endoscopic submucosal dissection (ESD) for a diagnostic therapy. The resected specimen revealed a white, elastic, nodular, submucosal mass. Histological study revealed a well-circumscribed lymph follicle in the submucosa invading the muscularis mucosa and centrocytelike cells and epitheliotrophic proliferation (lymphoepithelial lesion, LEL) invading into the mucosa with obliteration of gastric glands (Fig). While the LEL was initially interpreted as poorly differentiated adenocarcinoma, the pathological evidence obtained from ESD established the diagnosis of a MALToma of the stomach (c-stage IE). After eradication of H. pylori with antibiotics, the patient has had no local or distant recurrences during the subsequent two years of surveillance follow-up. Discussion: This case is unique because of localized gastric MALToma. It usually presents as multi-focal disease in the stomach and systematic gastric biopsy is crucial for diagnosis. There are no characteristic endoscopic findings and in epithelial tissues, the neoplastic cells typically infiltrate the epithelium forming a LEL. The risk of misdiagnosing LEL in epithelium as poorly differentiated gastric adenocarcinoma in endoscopic biopsy was previously reported. In this localized MALToma case, theoretically, since gastric MALToma develop from mucosal associated lymphoid tissue, we believe ESD was adequate for the definite tissue diagnosis.Figure: No Caption available.