Intestinal polyps disease

　　First, etiology

　　There are many classification methods for colorectal polyps, which can be divided into solitary and multiple according to the number of polyps. However, the most widely used method in China and abroad is based on Morson's histological classification, which divides colorectal polyps into tumorous, hamartomatous, inflammatory, and hyperplastic (Table 1). The greatest advantage of this classification method is that it unifies colorectal polyps as adenomas, while other non-tumor polyps are collectively referred to as polyps. This classification can clearly distinguish the pathological nature of colorectal polyps and has greater guiding significance for treatment.

　　In China, adenomatous polyps are the most common, while some foreign reports indicate that proliferative polyps are the most common, with an incidence rate as high as 25% to 80%; the incidence rate of proliferative polyps in adults is at least 10 times higher than that of adenomas, but some scholars have found that the incidence rate of adenomas is 3 times higher than that of proliferative polyps during colonoscopy. According to research data, the occurrence of polyps may initially mainly occur in the distal colon, which can be verified from the fact that the left-sided polyps are often more than the right-sided ones in post-mortem examination materials. With the increase of age, polyps gradually develop from the left side to the right side.

　　2. Pathogenesis

　　The origin of adenomas is not yet fully understood. Initial studies have shown that deep crypt cells gradually develop into atypical hyperplasia as they migrate towards the surface. The normal crypt epithelium in the deep part is mainly expressed in sulfuric acid mucin, while the sulfuric acid mucin of adenomatous epithelium is more than that of sialic acid mucin. Recent studies have shown that blood group Ley antigen is diffusedly stained in many adenomas, while it is only seen in the deep crypts of normal mucosa with a positive reaction. The consistency of histochemical reactions between the adenoma epithelium and the deep crypt epithelium strongly supports the possibility that adenomas originate from the deep crypts. Another hypothesis for the origin of adenomas is eosinophilic epithelium, which is often located near the adenoma epithelium and shows a transitory phenomenon. Based on the sequential theory of colorectal adenoma → colorectal cancer, there is a sequential phenomenon from normal colorectal mucosa → tubular adenoma → tubular-villous adenoma → villous adenoma → colorectal cancer. It is believed that the occurrence of adenomas is initially mostly tubular adenomas, which gradually transform into tubular-villous adenomas and villous adenomas, and finally evolve into colorectal cancer. Canceration can also occur at the stages of tubular adenoma and tubular-villous adenoma.

　　Regardless of the location of the adenoma in the crypt, the proliferation of adenoma tissue is mainly towards the lumen to form an outward protruding mass. Although all adenomas start with a broad-based growth, as the adenoma grows larger, some adenomas become pedunculated or subpedunculated. In the descending colon and sigmoid colon, due to strong peristalsis and well-formed feces, it is easier to form pedunculated polyps at this site than at other parts of the intestine.

　　1. The histological characteristics of adenomatous polyps are not only the histological basis for the classification of adenomatous polyps, but also the basis for the diagnosis of adenomatous polyps. Adenomatous polyps are divided into tubular adenomas, villous adenomas, and mixed adenomas (i.e., tubular-villous adenomas). The histological sections of adenomatous polyps often show villous components, which are many delicate branches extending from the base of the lesion, with abundant mucus secretion visible. The core is composed of loose fibrous connective tissue, and the surface is covered with a single or multiple layered columnar epithelial cells. The amount of villous components is positively correlated with the malignancy of adenomas, so correctly evaluating the amount of villous components in adenomas is helpful for judging their potential for malignancy. It should be understood that the distribution of villous components in the same adenoma at different sites is not uniform, and the pathological diagnosis of the tissue obtained by biopsy at different sites can be different.

　　Histologically, tubular adenomas show early changes with dense arrangement of columnar cells in the crypts, with deep nuclear staining, a decrease or disappearance of goblet cells. As the lesion progresses, there is marked hyperplasia, elongation, branching, and expansion of the glands, with varying sizes of glandular cavities and hyperplasia of epithelial cells. They tend to protrude into the lumen, forming papillary structures; nuclear staining is intense, with a few nuclear mitoses, all located at the base, with a small amount of connective tissue stroma, small blood vessels, and inflammatory cell infiltration. Unlike tubular adenomas, villous adenomas usually originate from the surface epithelium of the large intestine, grow into the intestinal lumen, and form papillary protruding masses. Histologically, they show typical delicate villous structures, with villi often directly connecting to the mucosal surface, with a single or multilayered columnar epithelial cell layer on the surface, cells of unequal size and regular arrangement, nuclear staining intense at the base, with frequent nuclear mitoses, and the core of the villi is composed of fibrous connective tissue, containing an unequal amount of small blood vessels and inflammatory cell infiltration. Mixed adenomas show a tubular adenoma basis, mixed with villous adenoma components.

　　2, Canceration of colonic adenomas The canceration of adenomas is characterized by nuclear atypia, loss of polarity, increased nuclear-cytoplasmic ratio, and the appearance of a large number of nuclear mitotic figures. According to the depth of invasion, they can be divided into in situ cancer and invasive cancer, with the mucosal muscular layer as the boundary. The reason why in situ cancer does not metastasize is that there are no lymphatic vessels in the固有层 of the intestinal mucosa, so what is often referred to as adenoma canceration in clinical practice is usually for invasive cancer. The vast majority of colorectal cancers come from the canceration of colonic adenomas. The factors affecting adenoma canceration are mainly the degree of atypical hyperplasia, the size of adenomas, and the degree of villous component hyperplasia. Both the increase in adenoma size and the increase in villous components can exacerbate the degree of atypical hyperplasia. Adenomas with a diameter less than 1 cm rarely develop canceration. The canceration rate of tubular adenomas is relatively low, while the canceration rate of villous adenomas is about 5 times higher than that of tubular adenomas.

　　3, Familial multiple adenomatosis is a dominant autosomal hereditary disease. Under endoscopic examination, it is characterized by a large number of small adenomas, most of which are only a few millimeters in size, and a few are more than 1 cm. Morphologically, they are sessile half-circular, nodular elevations, with a smooth or lobulated surface, red in color and soft in texture, with or without pedicles, and dense ones showing a carpet-like structure. Histologically, they are basically the same as adenomas, with rare hyperplastic polyps, but a high incidence of cancer. Canceration will occur within 5 to 20 years, with an average age of 39 years, and multiple centers are more common.

　　4, Turcot syndrome is a syndrome characterized by multiple adenomas of the large intestine and malignant tumors of the central nervous system, which is an autosomal recessive inheritance, different from familial adenomatosis. The adenomas in this syndrome also show a distribution throughout the entire large intestine, but the number is less and scattered. There are rarely more than 100 before the age of 10, and more than 100 after the age of 10. The age of cancer development is early, generally below 20 years old, and it is more common in women.

　　5, Gardner syndrome consists of 4 lesions:

　　(1) Multiple adenomas in the large intestine.

　　(2) Osteomas (commonly found in the mandible, skull, and long bones).

　　(3) Desmoid tumors (commonly found in the mesentery after surgery).

　　(4) Dermatofibroma (including sebaceous cysts and epithelioid cysts, which are commonly found on the head, back, face, and limbs, and some may have dental malformations).

　　Some refer to the occurrence of all the above lesions as the complete type, while if two of the latter three lesions occur, it is considered an incomplete type, and if only one occurs, it is a simple type. It is generally believed that the heredity, age of onset, number, type, distribution, and cancer risk of colonic adenomas are the same as those in general familial adenomatous polyposis patients. Clinically, compared with familial adenomatous polyposis, the onset age of colonic adenomas is later, and they can appear after extraintestinal symptoms, with fewer adenomas.

　　6, Peutz-Jeghers syndrome, also known as hamartomatous polyposis, is an autosomal dominant genetic disorder, but only half of the cases have a family history in clinical practice. Its characteristics are: multiple gastrointestinal polyps; hereditary; the skin and mucous membranes of specific sites appear melanotic spots, which are often found around the lips and buccal mucosa, with clear edges and a diameter of about 1-2mm. The histological features are an increase in the number of melanocytes in the dermal basement membrane and melanin deposition. Most polyps exceed 100, and they are most common in the small intestine (64%-96%), followed by the large intestine (30%-50%). This disease can also lead to cancerous changes.

　　Weight loss and anemia are the main complications. They can cause increased frequency of bowel movements or a feeling of rectal prolapse. In some rare cases, colonic adenomas may cause intussusception and abdominal绞痛. The symptoms of small intestinal polyps are often not obvious, and they may manifest as recurrent abdominal pain and intestinal bleeding. There may be fever, anemia, weight loss, and other systemic chronic inflammatory manifestations. Lymphoma patients may have chronic fever and gastrointestinal bleeding. Carcinoid tumors can lead to carcinoid syndrome, etc.

　　Most colonic adenomatous polyps are asymptomatic, without any clinical symptoms. A few cases may present with changes in bowel habits, bloody and mucous stools, loose stools, increased frequency, and varying degrees of abdominal discomfort. Occasionally, there may be abdominal pain, weight loss, anemia, and other systemic symptoms. In extremely rare cases, a mass may protrude from the anus during defecation. Cases with a family history often have a suggestive role in the diagnosis of polyps. Some typical extraintestinal symptoms often suggest the possibility of polyposis. Some patients often seek medical attention due to extraintestinal symptoms and should not be ignored. Due to the few clinical symptoms of this disease, it is easy to be overlooked or misdiagnosed. Therefore, the diagnosis of colonic polyps should first enhance the understanding of the disease. Any unexplained hematochezia or gastrointestinal symptoms, especially in middle-aged and elderly men over 40 years old, should be further examined to improve the detection rate and diagnosis rate of colonic polyps.

　　Recent studies have reported that long-term oral administration of sulindac and other non-steroidal anti-inflammatory drugs has a preventive effect on the recurrence of polyps, but attention should be paid to the other side effects of the drug. At the same time, the efficacy of this preventive treatment needs to be observed in large-scale cases.

　　Change the habit of eating meat and high-protein foods as staple foods. Eat less high-fat foods, especially control the intake of animal fats. Reasonably arrange daily meals, eat more fresh fruits and vegetables that are rich in carbohydrates and rough fibers, and appropriately increase the proportion of coarse grains and mixed grains in staple foods. It is also necessary to actively exercise, find suitable exercise methods, enhance physical fitness, improve immunity, relax oneself, relieve stress, and maintain a good mental state.

　　1. Fecal occult blood test:Its diagnostic significance is limited, with many false negatives, and positive results can provide clues for further examination.

　　2. X-ray examination:Barium enema can detect colonic polyps through the filling defect of barium, but it often cannot correctly classify and characterize the lesions.

　　3. Endoscopic examination:Endoscopic examination not only allows direct visualization of the fine lesions of the colonic mucosa, but also can determine the nature of the lesions through tissue biopsy and cytological brush examination, therefore, it is the most important means for the discovery and diagnosis of colonic polyps. All polyps found by endoscopic examination must undergo histological examination to understand the nature, type, and presence of cancer. Small or pedunculated polyps can be removed by biopsy forceps or snare forceps and sent for examination. Large or broad-based giant polyps are often only suitable for biopsy. Since the disease has a high incidence in the population, it is often found incidentally during colonoscopy or further examination of patients with gastrointestinal discomfort. If a polyp with a diameter less than 1 cm is found during colonoscopy, biopsy is usually required, and further treatment is based on the pathological results. If a polyp with a diameter greater than 1 cm is found, biopsy is not required, and the polyp is removed directly during colonoscopy. If a polyp is found in the sigmoid colonoscopy and the biopsy confirms it as an adenoma, further colonoscopy is required to exclude the presence of other adenomas or hyperplastic lesions in the proximal colon.

　　Due to the uneven distribution of villous components and the degree of atypical hyperplasia in different parts of the same adenoma, the lesions at the biopsy site cannot fully represent the overall situation. The absence of cancer at the biopsy site does not necessarily mean the absence of cancer elsewhere. Therefore, the degree of atypical hyperplasia and the absence of cancer in adenomas often require the removal of the entire tumor for a thorough section examination to be certain. The pathological results of the biopsy can be used for reference, but are not the final conclusion. In clinical practice, it is quite common for the preoperative biopsy results to be different from the postoperative pathological diagnosis in villous adenomas.

　　1. It is not very suitable to drink milk.

　　2. Edible fungi such as silver ear, black fungus, mushrooms, and lingzhi can be used regularly to enhance immunity.

　　3. In terms of diet, it is necessary to strengthen the spleen, transform dampness, and break blood stasis. Use hawthorn to improve appetite and relieve stagnation, and the effect is better when配合麦芽、鸡内金等. To strengthen the spleen and transform dampness, you can use山药、薏苡仁、茯苓.

　　4. Honey has high health value and is good for the intestines.

　　5. Eating should be regular, generally only eat to 7/10 full, and eat appropriate amounts of杂粮粗粮.

　　6. Folk remedies use ginger tea to treat dysentery, which has a bidirectional immune effect.

　　7. Avoid fried foods, excessively fatty foods, foods containing colorants, preservatives, flavorings, saccharin, pickled, and deteriorated waste food.

　　First, treatment

　　1. Non-surgical treatment:The principle of treating colonic polyps is to remove the polyps as soon as they are found. The choice of treatment plan depends on the location, whether it has a pedicle, size, and potential malignancy. Non-surgical treatment is mainly endoscopic high-frequency electrocoagulation polypectomy, or laser or microwave resection. Before the operation, the intestines should be cleaned, and the operation should be performed under the condition that there is no obstacle in the coagulation mechanism. After the operation, a small amount of liquid food or fasting for 1 to 3 days should be taken, the amount of activity should be restricted, and hemostasis (such as 3.0g/d of phenolsulfonate) should be given intravenously, anti-inflammatory (antibiotics for Gram-positive bacteria), and intestinal mucosal protection (such as bismuth subgallate) treatment should be given, and the color of stool and bowel sounds should be closely observed, and attention should be paid to whether bleeding or perforation occurs.

　　(1) High-frequency electrocoagulation resection: According to the shape, size, and number of polyps, as well as the presence, length, thickness of the pedicle, the following methods can be adopted.

　　① High-frequency electrocoagulation incineration method: Mainly used for multiple hemispherical small polyps.

　　② High-frequency electrocoagulation loop resection method: Mainly used for pedunculated polyps.

　　③ 'Close contact' removal method: Mainly used for long pedicle large polyps that are difficult to suspend in the intestinal lumen, using the large polyp close contact intestinal wall electrocoagulation resection method.

　　④ High-frequency electrocoagulation thermal biopsy forceps method: Currently rarely used.

　　(2) Biopsy forceps removal method: Mainly used for single or a few spherical small polyps, simple and easy to operate, and can also take living tissue for pathological examination.

　　(3) Phased and batch removal method: Mainly used for patients with 10 to 20 polyps who cannot be resected at one time.

　　(4) Laser ablation and microwave thermotherapy: Suitable for cases where no histological specimens need to be retained.

　　2. Surgical treatment:Patients with polyps can adopt a combined treatment method of endoscopy and surgery, which can achieve the treatment goal while maintaining the normal function of the large intestine. The indications for surgery are often: adenomas with more than 10 multiple, large in size, and localized in a certain segment of the intestine; large polyps blocking most of the intestinal lumen, with unclear pedicle or broad-based adenomas, with a base diameter greater than 2cm. The recurrence rate of colorectal adenoma after resection is high, and there is a possibility of multiple adenomas. A detailed clinical follow-up plan should be formulated according to the patient's histological type, so as to detect the lesions early and provide timely treatment.

　　Malignant colonic polyps refer to adenomas containing invasive cancer cells and cancer cells penetrate through the mucosal muscular layer into the submucosa. Compared with adenomas with severe atypical hyperplasia, the cancer cells of malignant adenomas are not confined to the mucosa, so there is a possibility of metastasis. The indication for surgical treatment should be determined according to whether there are residual cancer cells or lymph node metastasis at the base of the polyp resected under colonoscopy. When a polyp is suspected to be malignant under colonoscopy, the endoscopist should first estimate whether it can be resected under the endoscope. Pedunculated or small sessile polyps can be completely resected, while large sessile polyps should be biopsied first. After the polyp is resected, all tissues should be sent for pathological examination (i.e., total tumor pathological examination), and the detailed description of the location of the polyp should also be provided, because if the polyp is found to be malignant, then surgical treatment is necessary. Indian ink can also be injected into the intestinal wall at the site of polyp resection, leaving a permanent locational marker for possible future surgical sites.

　　3. Regular Follow-up:Since colorectal polyps, especially adenomatous polyps, have been recognized by scholars as precancerous lesions or conditions, regular follow-up of colorectal polyp patients has been raised to a high level of understanding for the prevention and treatment of early colorectal cancer. Regular follow-up of colorectal polyps, especially adenomatous polyps, is an important link in preventing polyp malignancy. The re-detection rate of polyps is relatively high, with reports from abroad ranging from 13% to 86%. The newly detected polyps include some recurrent polyps that are regrown from residual polyps, and some are new colorectal polyps and missed polyps. To maintain a state without polyps in the intestines and prevent the occurrence of colorectal cancer, it is necessary to develop an economical and effective follow-up plan.

　　II. Prognosis

　　At the third International Colorectal Cancer Conference held in Boston, the colorectal adenoma group discussed and recommended a detailed plan. They pointed out that the risk of recurrence of new adenomas and local adenoma recurrence in adenoma patients after adenoma resection varies, so they should be treated differently.

　　1. Low-risk group:Any single, pedunculated (or broad-based), but

　　2. High-risk group:The following conditions are considered high risk: multiple adenomas, adenoma diameter > 2cm, broad-based villous or mixed-type adenomas, adenomas with severe atypical hyperplasia or associated with in situ carcinoma, and adenomas with invasive cancer. The follow-up plan for the high-risk group is to perform endoscopic examination 3-6 months after adenoma resection, if negative, re-examine every 6-9 months, if negative again, re-examine after 1 year, if still negative, re-examine every 3 years, and during this period, occult blood test in feces should be performed annually.