S2060 Localized Lymphoid Hyperplasia of the Colon Mimicking MALT-Lymphoma in a Patient With Ulcerative Colitis

Abstract

Introduction: Localized lymphoid hyperplasia (LLH) of the colon, also known as rectal tonsil, is a rare clinical entity. When present, LLH almost always presents in the rectum. LLH can appear as a polyp of varying sizes, nodule, or a mass. Rectal bleeding is usually the most common presenting symptom of LLH. In most cases, LLH resolves without any intervention; however endoscopic differentiation from extra-nodal marginal zone lymphoma of mucosa-associated lymphoid tissue (MALT) is challenging. We present a case with ulcerative colitis (UC) having a diagnosis of LLH of rectum. Case Description/Methods: A 54-year-old male with a history of ulcerative colitis for 6 years was admitted to our hospital after an observation of abnormal metabolic activity in the rectum on a positron emission tomography/computed tomography (PET/CT) scan. He had a past medical history of squamous cell carcinoma of the lung, for which he underwent resection 16 years prior to his present admission. In his subsequent follow-ups, the present PET/CT scan was performed and he was consulted to our division. His UC was under remission and he had no symptoms. His laboratory tests were unremarkable and CMV viral tests were negative. His medications included oral mesalamine 4 g/d. He never required steroids or any immunomodulatory therapy. A decision to perform a colonoscopy was made. A horseshoe-shaped area with ulceration in the middle was observed in the rectum. Multiple biopsies were taken. Histopathological analysis revealed superficial mucosal fragments of lymphoid hyperplasia between lamina propria and submucosa. Cytokeratin AE1/AE3 immunostaining was negative, and dysplasia was not present. The patient was diagnosed with LLH of the rectum. A control colonoscopy was scheduled for 3 months later, and the regression of the lesion was observed (Figure). Discussion: Despite rectal bleeding being the most common presentation of LLH, patients can be asymptomatic, as seen in our case. LLH is usually considered a benign lesion, however some reports suggest its association with MALT-lymphoma. Histopathological analysis is essential to exclude a malignant process, and to make the correct diagnosis.Figure 1.: A: Horseshoe-shaped area with ulceration in the middle in rectum. B: Control rectoscopy showed no lesion. C: Hematoxylin-eosin staining of the lesion shows lymphoid nodular hyperplasia.