An anal polyp, also known as a rectal polyp, is an abnormal, mushroom-like growth sticking out from the mucous membrane that lines the anus or colon. It typically starts as a microscopic and benign growth, but over time it can become malignant. Polyps need to be identified and removed as quickly as possible. The four types of anal polyps are inflammatory, hyperplastic, tubular adenoma or adenomatous, and villous adenoma or tubulovillous adenoma.
Inflammatory anal polyps are common in people with Chrohn's disease. It is actually an enlarged mass of mucous membrane that resembles a polyp, but isn’t in fact one. This mass is a reaction to some type of chronic inflammation in the anus. Inflammatory polyps are completely benign and cannot lead to cancer.
Hyperplastic polyps feature rapidly growing cancerous tissue that could potentially become malignant. Since a hyperplastic polyp is small, it carries a lower risk of danger. Due to its size it cannot be detected by a conventional colonoscopy, which means a doctor must perform a biopsy instead.
Tubular adenoma, or adenomas polyps, are the most common form of anal polyps, and make up 70% of all diagnosed anal and rectal polyps. This type of polyp manifests itself without any symptoms, which makes detection much harder. To make matters worse, adenomas polyps grow very slowly and can take years to become cancerous, after which they can be fatal. Individuals with a family history of tubular adenoma should undergo annual colon cancer screenings.
A villous adenoma, or tubulovilluous adenoma, polyp is present in only 15% of cases, but it is the most dangerous type of polyp. It is the highest risk polyp and is a much larger and threatening growth than the other types of polyps. Unlike the other polyps, villous adenomas usually attach themselves directly to the wall of the anus, which makes them more difficult to remove. Most cases of villous adenoma require surgery.
The treatment for an anal polyp differs based on which type it is. Individuals can lower their risk of polyp growth by obtaining annual cancer screenings and eating more fiber and calcium. Adding more calcium to the diet can potentially reduce the risk developing a polyp by 25%, but an increased calcium level can increase an individual’s risk for other cancers.