Colonic perforation following polypectomy of a gastrointestinal follicular lymphoma masquerading as a colon polyp.

INTRODUCTION: The gastrointestinal (GI) tract is the predominant site for primary extranodal non-Hodgkin lymphomas (NHL), accounting for 5-10% of all extranodal disease. CASE: A 74-year-old man underwent colonoscopy for a positive fecal occult blood test. Colonoscopy revealed a 3.5-cm polyp in the descending colon and was removed by snare cautery polypectomy. Post-polypectomy site showed a 0.3-0.5-cm mucosal defect. Five endoclips were applied to close the mucosal defect. The patient remained stable during subsequent intensive monitoring and never required surgical intervention. Pathology of the polyp revealed follicular lymphoma (FL) involving the lamina propria of the mucosa with extension into the submucosa. The patient had no systemic symptoms, and staging for NHL with contrast computerized tomography of the chest, abdomen, and pelvis revealed no evidence suggestive of lymphoma. DISCUSSION: Approximately 6-20% of all primary GI-NHL are in the colon. The frequency of GI-FL accounts for 1-3.6% of all GI-NHL. After a search of the current literature, there have been no cases of a follicular lymphoma presenting solely as an isolated colon polyp. Likewise, bowel perforation due to polypectomy of such polyps has never been cited. Retrospectively, the diagnosis and extent of the polyp could have been established using endoscopic end-to-end forceps biopsy and/or endoscopic ultrasound with a radial scanning catheter probe and fine-needle aspiration of the lesion. Such a diagnosis could have changed the strategy for endoscopic removal of the polyp. Our case is interesting because it is the first report of a follicular lymphoma presenting as a single isolated colon polyp involving all layers of the colonic mucosa.