Polyps of the colonK63.5

Colonic polyps are benign or malignant protrusions of mucous membrane that protrude into the lumen of the colon. They can be broad-based or stalked and vary considerably in size. Colonic polyps can be solitary, but often multiple, and are found mainly in the rectum and sigmoid. In case of multiple occurrence, a hereditary polyposis syndrome must be excluded.

Familial adenomatous polyposis (PAP), an autosomal-dominant inherited disorder that is an obligatory precancerous condition, is a special form.

The polyps of the colon are classified according to histopathological criteria into:

• Inflammatory polyp (granulation tissue polyp)
• Hyperplastic polyp (focal hyperplasia, harmless lesion, usually located in the distal colon)
• Neoplastic polyp (true epithelial or mesenchymal tumor). This polyp type is classified according to histological criteria as follows
• Hamartoma (congenital polyps, common with genetic syndromes)

• Classical adenomas
  • Tubular adenoma (50%) - usually polyps measuring up to 1.0 cm (rarely >2.0 cm) with a low, but already significantly increased risk of carcinoma compared to normal findings (45% of adenomas)
  • Tubulovillous adenoma (35%) - usually stalked polyps measuring up to 2.0 cm in diameter, which have a degeneration frequency more than twice as high as that of the tubular adenoma (40% of adenomas)
  • Villous adenoma (15%) - mostly broad-based polyps (usually >2.0cm) with mucus formation, which have the highest degeneration frequency among colonic polyps (10% of adenomas)
  • Sessile serrated adenoma: flat new formation barely raised above the level of the mucosa, mainly in the right colon.
  • Traditionally serrated adenoma: polypose neoplasm with serrated toothed surface
  • Mixed adenoma: combined adenomatous-hyperplastic neoplasia.

Polyps are found in the dissection material in 10% of adults.

The growth of polyps in the colon usually begins from the age of 40; >60 years: 30% infestation; >70 years: 75% infestation - in Western Europe and the USA. In other parts of the world intestinal polyps are rather rare. m>w;

>50% of polyps are detectable in the rectum; with a further increase after oral examination the frequency of polyps decreases. Nevertheless, a diagnostic colonoscopy is only meaningful if there is insight up to the Bauhin valve.

Colonic polyps usually do not cause any symptoms. Only when there is a significant space requirement or accelerated growth can complications such as bleeding (evidence: blood in the stool) and ultimately obstruction (ileus) occur.

The detection of polyps is mainly done endoscopically, whereby the complete colonoscopy has the highest sensitivity. In this case, direct diagnostic-therapeutic intervention is also possible. If a polyp is detectable, at least one other colonic polyp is detectable in 1/3 of these patients.

In the case of generalised polyposis, the diagnostic procedure should be extended and used to clarify a possible polyposis syndrome. In addition to an oesophagogastroduodenoscopy, an MRI of the small intestine (hydro-MRI) or a capsule endoscopy can be performed.

The aim of therapy is the removal of a colonic polyp in healthy people. This can be done within the scope of diagnostic colonoscopy. Polyps with a diameter of less than 0.5 cm can be completely removed with biopsy forceps. Larger polyps (>0.5cm) are removed using a diathermy loop.

If safe diathermy ablation is not possible for larger polyps, a mucosectomy can be performed endoscopically.

The prognosis of non-hereditary polyps is good if they are removed in time. Control examination after 3 years. If the control examination is inconspicuous, further controls after 5 years

In most cases, colonic polyps are symptom-free. They are therefore mostly accidental findings during a colonoscopy. Their recurrence rate is 30-50% and depends on adenoma-associated factors (villous architecture, degree of dysplasia, location, size and number of adenomas) and on 3 other parameters: age, BMI (body mass index) and fasting blood glucose.

Each removed colonic polyp must be subjected to a histopathological examination. The questions of this examination are:

• Complete ablation in healthy individuals?
• Type of polyp?
• Breakthrough of the polyp into the submucosa?
• If endoscopic ablation of a polyp is not possible, different surgical resection procedures (minimally invasive surgery, surgery with laparotomy) are used, depending on the distinction between "low-risk" or "high-risk" lesions.

About 2-30% of colorectal carcinomas (KRK) develop at the base of a serratated adenoma (serratated carcinogenesis pathway).

An adenoma is not considered malignant as long as the lamina muscularis mucosae is intact. If this is broken through, an invasive colon carcinoma is already present by definition. The invasion of dysplastic cells into the lamina propria without rupture of the lamina muscularis mucosae counts as high-grade epithelial dysplasia (see below)

Hamartomas (congenital "tumor-like" malformations) are more common in genetic syndromes.

The dominant hereditary combination of colon polyps and multiple atheromas is called Oldfield's disease.