1600 Follicular Lymphoma Presenting as a Colon Polyp

Abstract

INTRODUCTION: Follicular lymphoma (FL) is the second most common type of Non-Hodgkin's lymphoma (NHL). There are two types of follicular lymphoma, nodal and extranodal. The gastrointestinal (GI) tract is the most common site of extranodal NHL and accounting for 30%-40% of all extranodal NHL. GI-FL comprises of only 1 to 4% of GI-NHL with less than 400 reported cases. GI-FL primarily involves the duodenum, distal ileum, and stomach. A colon is an uncommon place for GI-FL with less than 20 cases reported in the literature. We present a case of GI-FL identified on colonoscopy as a pedunculated polyp. CASE DESCRIPTION/METHODS: A 72-year-old female was seen for a positive stool occult test. She denied blood in the stool, abdominal pain, any weight loss, fatigue, night sweats, fevers, and diarrhea. She had occasional constipation which resolved with a stool softener. Physical examination was unremarkable without any palpable lymph nodes or organomegaly. During the colonoscopy, a 1.5 cm benign appearing pedunculated polyp in the mid-transverse colon was found (Figure 1). Primary histology of the polyp revealed lymphoid aggregates compatible with a lymphoid polyp. Diagnosis of GI-FL was later confirmed by immunohistopathological staining. Positron emission tomography (PET) scan showed aortocaval lymphadenopathy. The diagnosis of follicular lymphoma grade 2 stage IV is made. The oncologist has scheduled a bone marrow biopsy with consideration to immunochemotherapy. DISCUSSION: Colonic GI-FL is quite a rare disease with increasing incidence. Most patients are asymptomatic and diagnosed during endoscopy. The most common endoscopic appearance is 1 to 2 mm whitish polypoid nodules scattered or confluent together forming large nodules. Other appearances of GI-FL may include mass lesions with or without ulcer, lymphomatous polyposis, or polyps. These endoscopic features are also seen in lymphoid hyperplasia, MALT, mantle cell lymphoma. Immunohistopathological testing is the only way to confirm the diagnosis. GI-FL stains positive for CD10, CD19, CD20, and CD22, and bcl-2. It stains negative for cyclin D1 and CD5. PET scan is used for initial staging and surveillance of disease. GI-FL is an indolent lymphoma with favorable survival outcomes. A “watch and wait” approach is typically adopted. GI-FL presenting as a pedunculated polyp is an extremely rare presentation. Clinicians should be cognizant of endoscopy and immunohistopathological features of GI-FL.