Rectal Tonsil

Abstract

A 6-year-old girl was referred to our hospital with an 8-week history of intermittent bright red rectal bleeding. Rectal examination revealed a sessile mass within the lower rectum at 4 cm from the anal verge. Otherwise, she was an alert girl without any other symptoms. In addition, her clinical examination and laboratory studies were completely normal. A complete colonoscopy with ileal intubation revealed a sessile rectal polyp (Fig. 1), which was removed by standard electrocautery settings without any complications. Histologic examination revealed a flattened superficial mucosa from underlying expansive lymphatic growth caused by follicular hyperplasia (Fig. 2) with intermingled reactive blasts, which may mimic different lymphoproliferative lesions including low- or high-grade lymphomas. Immunohistochemistry (CD20, CD3, bcl-2, bcl-6, CD23, Ki-67, CD30) and in situ hybridization (κ, λ light chains) proved the benign nature of lesions.FIGURE 1: The colonoscopic appearance of the polyp in the distal part of the rectum.FIGURE 2: The low-power view of reactive follicular lymphoid hyperplasia underlying flattened rectal mucosa with nonspecific inflammatory changes (Kreyberg, original magnification ×100).The localized lymphoid hyperplasia of the large intestine is also known as rectal tonsil (RT), benign lymphoid polyp, and lymphoid polyp (1). RTs are located mainly in the rectum, just above the dentate line. They often cause intermittent rectal bleeding but rarely any abdominal pain. Endoscopic differentiation from lymphomas is not possible. Histologic distinction between RT and different B-cell lymphomas, especially mucosa-associated lymphoid tissue-type or diffuse large B-cell lymphoma, also is challenging (2). Immunohistochemical and genotypic studies are necessary to prove the reactive nature of the lesion. Published cases of RT in children are scarce (2). The presented case shows that RT also appears in children and that careful histologic examination including the use of immunohistochemistry and genotypic studies is necessary to avoid overdiagnosis and overtreatment.