[Endoscopic mucosal resection of localized plasmablastic lymphoma with early rectal cancer:a rare case report and literature review].

A 79-year-old male with a positive fecal occult blood test result underwent total colonoscopy, which revealed a 15-mm-semipedunculated polyp in the rectum. The polyp appeared to be an adenoma using narrow-band imaging observation in magnifying endoscopy, although a 3mm reddish segment with a different surface structure was identified adjacent to the base of the polyp. En-bloc endoscopic mucosal resection (EMR) was performed. From the pathological evaluation using the specimen, the polyp was mainly a tubular adenoma with an adenocarcinoma component within the lesion. Additionally, a tiny plasmablastic lymphoma (PBL) component, which was positive for CD45, CD79a, CD30, CD38, MUM1, and lambda light chain;negative for CD3, CD5, CD20, CD56, CD138, cyclin D1, PAX5, IgG, IgA, IgM, IgE, HHV8, and kappa light chain, coexisted near the stalk. The proliferation index using Ki-67 immunohistochemistry was approximately 80%. Furthermore, Epstein-Barr virus-encoded RNAs were identified in in-situ hybridization, although the human immunodeficiency virus was not detected. The patient received contrast-enhanced computed tomography (CT) and positron emission tomography-CT (PET-CT) follow-ups after treatment without recurrence for two years. This is the first report of gastrointestinal PBL that could be treated using EMR.