Purpose: A 56 year-old male presented for a routine screening colonoscopy. A 1.5cm polyp found in the sigmoid colon was excised. Analysis of the polyp demonstrated a dense lymphoid infiltrate involving the submucosa and lamina propria. The infiltrate coalesced into vague nodular pattern structures resembling follicles with destruction and gland drop-out appreciated by immunostains of CD20 and CD3. Portions of colonic tissue with extensive infiltration of mainly small mature lymphocytes with scattered larger lymphocytes displayed prominent nucleoli. Immunohistochemical stains showed B-cells positive for CD10, CD20, Bcl-2, Bcl-6. The proliferation index Ki-67 was low overall, ranging from 5% to 15%. The CD3 stain highlighted small T-cells outside the follicular structures. The CD21 stain revealed residual disrupted follicular dendritic meshwork. Stains for cyclin-D1 on P53 were negative. The morphology in conjunction with immunohistochemical studies was diagnostic for follicular lymphoma, grade 1-2/3. No evidence of large cell transformation in the specimen.Staging for NHL with CT revealed no evidence suggestive of lymphoma. Primary GI lymphoma is a relatively rare disease, accounting for 11 to 34% of all non-Hodgkin's lymphomas. These lymphomas are mostly B-cell type with the predominate subtype being the diffuse large-cell type.Primary follicular lymphomas (FL) of the GI tract are very rare, accounting for less than 7% of all non-Hodgkin's lymphomas at this site. Primary follicular lymphoma of the GI tract has a predominant female preponderance. The most common site is the small intestine.The clinical manifestations and gross appearance of the lesions are related to the site of the GI involvement, with obstructing masses or wall thickening frequently seen with small intestine involvement and polyps in the colon and rectum.FL of the GI tract can be morphologically and immunophenotypically indistinguishable from nodal FL, with expression of CD20, CD10, and BCL2. As primary FL of GI tract is very rare, no definitive therapeutic approaches have been defined. Therapeutic interventions like surgery and chemotherapy are no indicated unless clinical symptoms are present or the disease is progressive.Figure: A: POSITIVE FOR CD20, CD10, Bcl-6, & Bcl-2. Ki-67=low (5 to 15%). CD21 & CD3 negative. Figure B: Sigmoid polyp.