A Rectal Tonsil Like No Other

Abstract

Rectal tonsil is a rare condition. Its etiology is unknown, but it is comprised of a reactive proliferation of lymphoid tissue. Here we present a case of large, bleeding rectal tonsil. A 33-year-old healthy female presented with a 3-year history of intermittent rectal bleeding. Initial colonoscopy revealed irregular granular-appearing rectal mucosa, which was partially circumferential and extended 10 cm from the anal verge. Biopsy showed atypical lymphoid infiltrate positive for CD-20 and bcl-2, concerning for low-grade B-cell non-Hodgkin lymphoma. Endoscopic ultrasound showed mild, diffuse wall thickening of the mucosal/submucosal layer. Biopsies confirmed reactive lymphoid hyperplasia with flow cytometry negative for clonal population. She continued to have rectal bleeding at 6-month follow-up. Repeat colonoscopy showed a circumferential area of severely granular mucosa from the dentate line to 5 cm from the anal verge. Biopsies again revealed reactive lymphoid hyperplasia with negative flow cytometry and FISH. Currently, the patient continues to be monitored with close follow-up. The rectal tonsil is a rare finding. The most common presentation is rectal bleeding. Our case is the largest lesion presented in the literature as majority of the lesions reported consisted of discrete small (< 6mm) polypoid lesions or nodules. Previous studies reported complete resection of these small discrete lesions and show no recurrence or lymphoma transformation. However, the follow up for these studies is brief. Rectal tonsil should be distinguished from MALT lymphoma and other lymphoid diseases with malignant potential. Our patient is unique as the lesion was large and circumferential; therefore the patient elected to remain under close surveillance. It is important to continue to surveillance of these patients to understand long-term outcomes.Figure: Colonoscopy: Rectal tonsil.Figure: Colonoscopy: Rectal tonsil (retroflexion).