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Multiple lymphomatous polyposis is considered to be a rare condition, with most of the cases being extranodal counterpart of mantle cell lymphomas. We report a rare case of multiple lymphomatous polyposis of the gastrointestinal tract in which the patient presented with abdominal pain and bloody diarrhea. Computer tomography of the abdomen showed circumferential wall thickening with intramural mass involving caecum & ascending colon with enlarged pericolonic lymph nodes. The patient underwent right hemicolectomy. Immunohistologic findings were characteristic of MALT lymphoma. Microscopic examination of polypoidal masses and mesenteric lymph nodes revealed infiltration by pleomorphic, atypical lymphoid cells which were CD20 positive and negative for CD3, CD10, Cyclin D1. Lymphoepithelial lesions were also noted. Careful endoscopic evaluation and histopathological review along with an immunohistochemical panel is extremely useful for accurately diagnosing such cases and avoiding unnecessary surgery and inappropriate therapy.

The risk of misdiagnosing neoplastic cells typically infiltrating an epithelium forming a lymphoepithelial lesion as poorly differentiated gastric cancer in endoscopic biopsies, particularly in low-grade mucosa-associated lymphoid tissue (MALT) lymphomas, is described. A 76-year-old woman was referred for management of a poorly differentiated gastric adenocarcinoma. Diagnostic endoscopy in our unit showed a 2 cm raised, submucosal lesion with central erosion in the upper body of the stomach, but repeat biopsies of the lesion were interpreted as inflamed gastric mucosa and negative for malignancy. Systematic gastric biopsies to rule out any foci of MALT lymphoma changes were also negative. Therefore, endoscopic submucosal dissection was performed to obtain an accurate specimen. Histology revealed centrocyte-like cells and a lymphoepithelial lesion invading into the mucosa with obliteration of the gastric glands, which was initially interpreted as poorly differentiated adenocarcinoma.