Mucosal Prolapse / Cloacogenic Polyp
Definition
- Histopathologic features of rectal mucosal prolapse ranging from ulceration to polyp formation
Alternate/Historical Names
- Cap polyposis
- Hamartomatous inverted polyp
- Inflammatory cloacogenic polyp
- Localized colitis cystica profunda
- Solitary rectal ulcer syndrome
Diagnostic Criteria
- A variety of changes may be seen secondary to rectal mucosal prolapse
- Usually on anterior rectal wall within 12 cm of anal verge
- Rarely may occur in sigmoid or in stomas
- Superficial ulceration or erosion of mucosa
- May form a pseudomembrane
- Capillary congestion and thrombosis usually present
- Ulcers may be multiple
- Granulation tissue in high lamina propria
- Thickened, disorganized muscularis mucosae with extension into lamina propria
- Smooth muscle surrounds individual crypts
- Elastosis may also surround crypts
- Not normally present in lamina propria
- Crypts may be elongated and straight or markedly distorted
- May show cystic dilation
- May be serrated
- May form villiform hyperplasia
- Glands may be displaced into submucosa
- Has been termed localized colitis cystica profunda
- Lamina propria may accompany glands
- May simulate invasive carcinoma
- Mucus extravasation into stroma may be present
- May extend into lamina propria or submucosa
- Regenerating mucosal epithelium may appear adenomatous
- Adenomatous appearance is most marked in deep glands
- Maturation at surface is present, if not completely eroded
- Rare cases of prolapse apparently secondary to an adenoma
- Adenomatous appearance is most marked in deep glands
- Cloacogenic polyp refers to a combination of the above features that gives rise to an inflammatory reactive polyp that appears hamartomatous (because of the mixture of glands and muscle)
- Present in up to ¾ of cases
- Cap polyposis has been described in a few reports
- May represent numerous small prolapse polyps
- Located on edges of rectal mucosal folds
Robert V Rouse MD
Department of Pathology
Stanford University School of Medicine
Stanford CA 94305-5342
Original posting : 12/27/09
