Family adenomatous polyposis

Family adenomatous polyposis is a hereditary disease, which is based on the development of multiple polyps in the large intestine, leading to colon carcinoma at the age of 40 years. Usually, the disease is asymptomatic, but a gempositive stool can be observed. The diagnosis is established with a colonoscopy and genetic research. Treatment of familial adenomatous polyposis - colectomy.

[1], [2], [3], [4], [5], [6], [7]

What causes familial adenomatous polyposis?

Family adenomatous polyposis (SAP) is an autosomal dominant disease in which more than 100 adenomatous polyps lining the thick and rectum. The disease occurs in 1 to 8000-14 000 people. Polyps are present in 50% of patients aged 15 years and 95% at the age of 35 years. Malignization develops in almost all patients aged 40 years who have not been treated.

Patients may also experience various extra-intestinal manifestations (formerly called Gardner's syndrome), including benign and malignant. Benign lesions include desmoid tumors, skull or mandible osteomes, atheromas and adenomas in other parts of the gastrointestinal tract. Patients have an increased risk of malignancy of the duodenum (5-11%), pancreas (2%), thyroid (2%), brain (medulloblastoma less than 1%) and liver (hepatoblastoma in 0.7% of children under 5 years) .

Diffuse family polyposis is a hereditary disease manifested by a classical triad: the presence of a multitude of polyps (of the order of several cells) from the epithelium of the mucosa; family character of the lesion; localization of lesions throughout the gastrointestinal tract. The disease ends with the mandatory development of cancer as a result of malignant polyps.

Symptoms of diffuse (family) polyposis

In many patients, the symptoms of familial adenomatous polyposis are absent, but sometimes rectal bleeding, usually hidden, is observed.

Classification of familial adenomatous polyposis

There are many classifications of polyposis. Abroad, the classification of VS Morson (1974) is popular, in which four types are distinguished: neoplastic (adenomatous), hamartomic (including juvenile polyposis and Peitz-Egers' polyposis), inflammatory, unclassified (multiple small polyps). The objection is attribution to diffuse polyposis of diseases accompanied by the formation of pseudopolips, for example, with ulcerative colitis and Crohn's disease, since the formations are not related to true polyps.

The classification of VD Fedorov, AM Nikitin (1985), which takes into account not only the morphological changes, but also the stages of the development of the disease, spread in the domestic literature. Three forms of polyposis have been identified according to this classification: proliferative diffuse, juvenile diffuse and hamartomic.

Proliferative diffuse polyposis (predominance of proliferation in polyps) is a form, which in turn is divided into 3 stages, allowing to trace the dynamics of the disease right up to the development of cancer. It is in this group of patients that the greatest frequency of malignant polyps is. In the first stage (hyperplastic or miliary polyposis), the mucous membrane is strewn with minute (less than 0.3 cm) polyps, in which histopathologically against a background of unchanged mucosa, single crypts with hyperchromic epithelium and forming groups of glands of large size are revealed. As the epithelium proliferates, an ever larger group of crypts are involved in the process and polyps are formed. In the II stage (adenomatous polyposis) typical tubular adenomas up to 1 cm in size are formed, and in III (adenopapillomatous polyposis) - typical tubulosporous and villous adenomas. The index of malignancy of polyps in the first stage was 17%, and in the III stage - 82%. Malignancy developed sometimes in one, and more often in several polyps simultaneously.

With juvenile diffuse polyposis, malignancy is observed much less frequently (no more than 20%), and in the case of Peits-Egers syndrome - in isolated cases.

Special difficulties are faced by the morphologist when diagnosing, or rather when naming the variant of diffuse polyposis, since the same patient may have a combination of all varieties - from hyperplastic to juvenile. It is recommended to make a diagnosis for the "prevailing" polyps. Sometimes, patients with a hamartom or juvenile variant of polyposis are diagnosed with cancer. In these cases, malignancy occurs in the tubular or tubulosporal adenoma, which were single among juvenile and hamartomous polyps, or malignant adenomatous sites in mixed polyps occurred.

[8], [9], [10], [11], [12]

Diagnosis of familial adenomatous polyposis

The diagnosis is established if more than 100 polyps are found in a colonoscopy. In the diagnosis, a genetic test is needed to identify a specific mutation that should be detected in the first generation of relatives. If genetic testing is not available, relatives need a screening annual sigmoid survey, starting at age 12, while the frequency of the survey is reduced every ten years. If polyps are not found at the age of 50, the frequency of the examination is determined, as for patients with an average risk of malignancy.

Children of parents with family adenomatous polyposis need a screening test for hepatoblastoma from birth to 5 years with an annual control of the serum fetoprotein level and possibly ultrasound of the liver.

[13], [14], [15], [16]

Treatment of diffuse (familial) polyposis

When the diagnosis is established, the colectomy is performed. Total proktokoloktomiya with ileostomy or proctectomy with the formation of an ileoanal reservoir eliminates the risk of cancer. If subtotal colectomy is performed (removal of the larger part of the large intestine leaving the rectum) with ileorektalnym anastomosis, the remaining part of the rectum should be inspected every 3-6 months; new polyps should be removed or electrocoagulated. Aspirin or COX-2 inhibitors can help reduce the incidence of new polyps. If new polyps appear too quickly or in large quantities, removal of the rectum with the imposition of a permanent ileostomy is necessary.

After colectomy, patients need an endoscopy of the upper gastrointestinal tract every 6 months for 4 years, depending on the number of polyps (regardless of type) in the stomach and duodenum. It is also recommended that the annual physical examination of the thyroid gland and according to the ultrasound readings.