Anus and perianal area
Inflammatory diseases
Lymphoid polyp

Author: Arvind Rishi, M.D. (see Authors page)

Revised: 28 September 2017, last major update October 2014

Copyright: (c) 2002-2017, PathologyOutlines.com, Inc.

PubMed Search: Lymphoid polyp rectal

Cite this page: Rishi, A. Lymphoid polyp. PathologyOutlines.com website. http://pathologyoutlines.com/topic/anuslymphoidpolyp.html. Accessed October 18th, 2017.
Definition / general
  • Benign lesion which clinically resembles a polyp
  • Also called nodular lymphoid hyperplasia, pseudolymphoma, rectal tonsil
Sites
  • Most common in colon around the ileocecal valve due to the presence of abundant lymphoid tissue (prominent Peyer patches) in this region
  • Rectal and anal lymphoid follicles may be associated with inflammatory bowel disease or hemorrhoids
Pathophysiology
  • Reactive hyperplasia of mucosa associated lymphoid tissue
  • Associated with adenovirus infection, immunodeficiency (low IgA and IgM)
  • Multiple lymphoid polyps associated with familial adenomatous polyposis and Gardner syndrome (Gut 1983;24:333)
  • EBV associated with immunosupression may cause progression of the benign lymphoid follicle to lymphoma
Clinical features
  • Usually localized but can be diffuse
  • Rectal lymphoid polyps are usually asymptomatic but colonic lymphoid polyps may present with GI bleeding
  • Children: multiple lesions; larger lymphoid polyps may cause intestinal obstruction and intussusception
  • Adults: usually an isolated lesion
  • Subtypes: idiopathic (most common), reactive, hypogammaglobulinemia associated
Case reports
Gross description
  • Small polypoid or raised lesion, generally with a broad stalk or sessile
  • Surface erosions with acute inflammation over the lymphoid polyp / follicle clinically and endoscopically appears as an aphthoid ulceration, which is suggestive but not diagnostic for Crohn's colitis
Gross images

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Intestinal lymphoid polyps

Microscopic (histologic) description
  • Benign lymphoid follicles covered by columnar or transitional epithelium which may have reactive epithelial changes in the form of surface hyperplasia
  • Germinal centers may be seen in larger lymphoid polyps
  • Reactive lymphoid follicles may also be present in lamina propria (more commonly) or submucosa
  • Intraepithelial lymphocytes are commonly present over a lymphoid polyp and should not be considered as pathological
  • Intraepithelial neutrophils over a lymphoid follicle is a pathologic finding and should be reported in the final diagnosis
  • Presence or absence of dysplasia in the surface epithelium of the lymphoid polyp is not dependant on the nature of underlying lymphoid follicle
Microscopic (histologic) images

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Aggregates of atypical lymphoid cells

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Tingible body macrophages

Positive stains
  • CD20 in germinal centers, CD3 and bcl2 in peripheral zones
Negative stains
  • bcl2: negative in germinal centers (only scattered T cells in germinal centers stain positive)
Differential diagnosis
  • Most important differential diagnosis is reactive vs. neoplastic lymphoid polyp
    • Immunohistochemical stains are generally not required to prove the benign nature of the polyp
    • Reactive pattern of immunohistochemistry includes admixture of CD20+ cells (B cells) in the germinal centers and CD3+ cells (T cells) in the periphery
    • bcl2 should be negative in the germinal centers of a benign lymphoid polyp
    • Infiltrating pattern of monotonous lymphocytes into the muscularis mucosae is suggestive of MALT lymphoma, which has neoplastic lymphocytes that coexpress CD20 and CD43 but no marker is specific for MALT and the diagnosis is based on morphology, immunohistochemical stains and possibly molecular features (see also Stomach - MALT lymphoma)