Rectal Tonsil as a Cause of Recurrent Rectal Prolapse.

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A 9-year-old boy presenting with recurrent rectal bleeding and prolapse refractory to therapy for constipation was referred for colonoscopy. Initial work-up (magnesium, thyroid function, food allergies, celiac disease, and stool cultures) was negative. Five large rectal polyps were evidenced just above dental line. Due to the location of the lesions, a combined endoscopic/surgical submucosal resection of the lesions was performed (Fig. 1). Postoperative course was uneventful. The patient's symptoms resolved quickly. Histological examination after complete resection ruled out a malignant process, particularly extranodal marginal zone B-cell lymphoma (1–4), and confirmed the diagnosis of atypical mantle zone hyperplasia, also known as rectal tonsil (RT) (Fig. 2).FIGURE 1: Endoscopy showing polypoid lesions of lower rectum.FIGURE 2: Histology. (A) Rectal submucosal resection specimen showing nodular lymphoid proliferation in the mucosa and submucosa. Hematoxylin and eosin staining. (B) Positive CD20 immunohistochemical (IHC) staining, showing prominent B-lymphocyte proliferation. (C) Positive CD3 IHC staining demonstrating small T lymphocytes surrounding B-lymphoid nodules; (D) Bcl2 IHC staining showing negative-stained and disorganized germinal center (asterisk).RT corresponds to prominent and localized lymphoid tissue hyperplasia. The incidence seems to be more frequent in young children and adolescent. RT is associated with viral and bacterial infections (Giardia lamblia, Helicobacter pylori), food allergies, immune deficiency (IgA deficiency), and refractory constipation (5). RT can be asymptomatic or present with rectal bleeding, abdominal pain, or intestinal obstruction (3). Identification of predisposing factors and their treatment usually allows spontaneous resolution of the symptoms and sometimes regression of the lesions. Occasionally, resection is necessary to treat some complications as described in this unusual case (6–8).