Villous tumor of the colon is a benign neoplasm originating from the glandular epithelium of the mucous membrane. It is more often localized in the rectum. Over time, it often undergoes malignant degeneration. It is manifested by a large number of mucous secretions from the rectum. Sometimes the discharge is stained with blood. There may be a feeling of heaviness, constipation and a feeling of a foreign body. If the location is low, the tumor may fall out during defecation. The diagnosis is made on the basis of clinical symptoms, data from a finger examination of the rectum and the results of additional studies. The treatment is operative.
Villous colon tumor (villous polyp, villous adenoma, villous adenoma, polypoid adenoma, papillary adenoma, adenopapilloma) is a benign tumor originating from the epithelium of the mucous membrane. It makes up about 5% of the total number of colon polyps, usually occurs in old age. Most often located in the rectum, the second most common are villous tumors of the sigmoid colon. Women suffer less often than men. The risk of malignancy according to various data ranges from 60 to 90%.
A villous tumor of the colon is usually a compact node with a wide base, however, creeping forms can also be detected without the formation of an obvious tumor node, almost circularly covering the intestinal wall. The surface of the tumor is vulnerable to mechanical influences, the stroma has a large number of blood vessels, so the neoplasm often bleeds, and the presence of bleeding in itself is not a sign of malignancy. The treatment is carried out by specialists in the field of oncology and proctology.
Etiology and pathogenesis of a villous tumor of the colon
The causes of the development of villous tumors have not yet been established. Researchers point to an increase in the number of benign tumors of the large intestine over the past decades, linking this phenomenon with the deteriorating environmental situation and a decrease in the level of physical activity of the population. Another important factor that negatively affects the mucous membrane and increases the likelihood of developing villous tumors of the colon is a change in the nature of nutrition.
The diet of modern man is dominated by high-calorie foods with a high fat content and a small amount of fiber. This causes a decrease in intestinal peristaltic activity. Fatty acids in the process of cleavage turn into carcinogenic substances. Due to the slow progress of intestinal contents, the contact time of carcinogens with the mucous membrane increases, conditions are created that contribute to the development of tumor processes.
Pathological anatomy of a villous tumor of the colon
A villous tumor is a spongy pinkish-red formation on a wide base or thick stem, clearly delimited from the unchanged surrounding tissues. The surface of the formation is covered with thin fringed villi consisting of connective tissue fibers covered with a layer of epithelial cells. The stroma of a villous tumor of the colon is represented by connective tissue permeated with a large number of thin-walled blood vessels. The average size of the neoplasm is 1.5-5 cm, in some cases the polyp can reach 8-10 cm. Less often, a creeping form of a villous tumor of the large intestine is detected, in which the neoplasm does not protrude into the intestinal lumen, but spreads flatly along the surface of the intestine. The literature describes cases of creeping tumors with a length of more than 60 cm.
There are three types of villous tumors: without signs of proliferation, with signs of proliferation and with signs of malignancy. Tumor epithelial cells without signs of proliferation have clear boundaries, light cytoplasm and intensely colored nuclei. In neoplasms with signs of proliferation, the cells are located more closely, the boundaries are blurred, the nuclei are elongated. With malignancy, the morphological structure of the cells is clearly changed, the cells are polymorphic, epithelial areas penetrate into the underlying tissues.
Symptoms of a villous tumor of the colon
The disease can be asymptomatic for a long time. The main manifestation is abundant viscous glassy mucous secretions resembling egg white. The amount of mucus in large tumors in some cases reaches 3 liters per day. Accumulations of secretions in the rectum provoke the urge to defecate, the patient can empty himself several times a day with one mucus. Maceration and itching in the anus are possible. When traumatizing the surface of a villous tumor of the colon with fecal masses, mucous secretions are stained with blood. With frequent bleeding, anemia develops.
Patients complain of constipation and discomfort in the rectum. With large tumors that create an obstacle to the movement of fecal masses, pain syndrome may occur. Low-lying tumors sometimes fall out during defecation, and patients have to set them with their fingers. Significant losses of protein and electrolytes in giant neoplasms can cause dysproteinemia and violations of the water-salt balance. In some cases, partial or complete intestinal obstruction due to intussusception is possible.
The diagnosis is established by a proctologist on the basis of anamnesis, clinical manifestations and objective research data. A low-lying villous tumor of the colon can be detected during a conventional finger examination. With a high location of the neoplasm, a rectoromanoscopy or colonoscopy is required. Malignant degeneration is indicated by deformation of the intestinal lumen, loss of mobility of the bends of the intestine, increased bleeding, the presence of ulcers, fibrous and necrotic masses on the surface of the polyp.
If endoscopic methods of examination are unavailable, patients with suspected villous colon tumor are referred for irrigoscopy, however, this technique can give false negative results due to the impregnation of the tumor with barium mass. In doubtful cases, irrigoscopy is repeated after 1.5-2 months. The final diagnosis is made based on the results of a histological examination of a sample taken during an endoscopic examination, or microscopy of detached tumor sites found during the examination of feces.
Differential diagnosis of villous colon tumor is carried out with proctocolitis and other types of polyps. With proctocolitis, the discharge is serous-mucous, an admixture of pus may be detected in the mucus. A constant pain syndrome is characteristic, periods of deterioration are short-term, separated by light intervals. In other varieties of polyps, there is no abundant vitreous discharge. Differences in the endoscopic, histological and microscopic picture of the disease are revealed.
Treatment and prognosis for villous colon tumor
The treatment is operative, carried out as planned in a hospital setting. Small polyps of the rectum are removed endorectally using a loop, an electric knife or electrocoagulation. With large neoplasms, rectotomy or colotomy is performed. In some cases (with giant tumors, lack of complete confidence in the goodness of the neoplasm), it is necessary to resort to resection of the large intestine.
The prognosis for villous tumors of the colon is favorable. After surgery, complete recovery usually occurs, in some cases, relapses are possible. Patients are placed under medical supervision. During the first year after surgery, endoscopic examinations are carried out quarterly, and subsequently annually. In the absence of treatment, there is a high probability of malignant degeneration within a few years after the appearance of the tumor.