S3978 Beyond the Mucocele: A Rare Case of Non-Nodal Mantle Cell Lymphoma at the Appendiceal Orifice

Introduction: Mantle cell Lymphoma (MCL) is a rare and aggressive form of Non-Hodgkin’s B-cell lymphoma, which accounts for only 4%-9% of all reported cases of gastrointestinal Non-Hodgkin’s lymphoma. MCL is usually diagnosed by identifying a translocation of the CCND1 gene via immunohistochemistry. MCL is typically manifested as nodal disease, but non-nodal MCL can be found in the gastrointestinal tract. Typical symptoms of gastrointestinal MCL include constitutional symptoms, lymphadenopathy, nausea, vomiting, and change in bowel habits. This is a case of an atypical presentation of MCL found on screening colonoscopy. Case Description/Methods: The patient is a 59-year-old, asymptomatic, White woman who presented for an index screening colonoscopy and was found to have a 1 cm round, submucosal lesion with an ulcerated tip at the appendiceal orifice. The lesion appeared very friable and the endoscopist elected not to biopsy the lesion due to increased risk for bleeding and perforation. The lesion appeared to resemble a possible mucocele. A subsequent CT of the abdomen and pelvis confirmed the presence of a mass originating from the appendix with no radiographic evidence of metastases or lymphadenopathy. It was noted that the attenuation of the mass was higher than a typical mucocele. A positron emission tomography scan later confirmed no evidence of metastatic disease. The patient was then referred to a colorectal surgeon who performed a right hemicolectomy with appendectomy. Pathology of the appendiceal lesion revealed the diagnosis of Mantle Cell Lymphoma with no evidence of nodal disease. A subsequent surveillance colonoscopy performed 1 year after surgery showed no lesions with a well-healed ileocolonic anastomosis. The patient remains asymptomatic and continues to follow with oncology. Discussion: This case highlights the importance of keeping a broad differential diagnosis when encountering submucosal lesions of the gastrointestinal tract and reinforces the importance of following through with diagnosis on all submucosal lesions found on endoscopy. While rare, gastrointestinal lymphoma is a treatable and potentially curable disease if found early and managed appropriately.