Colon polyps in the elderly
Introduction
Introduction to colon polyps in the elderly Colorectal polyps are a general term for the bulging lesions on the surface of the large intestine. They only indicate the appearance of the naked eye and do not indicate the pathological nature. The polyps in the gastrointestinal tract are most common in the large intestine, especially in the colon and sigmoid colon. The size can be from 2mm to 10cm in diameter. Some colorectal polyps are benign epithelial tumors belonging to the intestinal mucosa, which are potentially malignant and have practical significance for the prevention and treatment of tumors. basic knowledge Sickness ratio: 0.5% Susceptible people: the elderly Mode of infection: non-infectious Complications: Intussusception Intestinal obstruction
Cause
The cause of colon polyps in the elderly
Living habits (20%):
The incidence of fibrous polyps in food is less, and vice versa. Smoking is also closely related to adenomatous polyps. A small adenoma occurs in the smoking history within 20 years, and more than 20 years in smoking history. A large adenoma.
Genetic (10%):
The occurrence of certain multiple polyps is genetically related. The patient inherits the defective APC allele from the parental germ cells, and another APC allele in the colon epithelium is normal at birth. When the allele is mutated, an adenoma occurs at the site of the mutation. This mutation is called a somatic mutation.
Embryo abnormality (5%):
Juvenile polyposis is mostly hamartoma, which may be related to abnormal embryonic development.
Age (20%):
The incidence of colon polyps increases with age.
Infection (5%):
It has been reported that the occurrence of adenomatous polyps is associated with viral infection.
Pathogenesis
1. Types of colorectal polyps
(1) hyperplastic polyps: hyperplastic polyps are the most common polyps, also known as metaplastic polyps, distributed mainly in the distal large intestine, generally small, less than 1cm in diameter, small in diameter less than 0.5cm Among the polyps, 90% are hyperplastic polyps, but according to the surgical resection specimens, the polyps of surgically removed polyps are mostly larger than 10%, and the shape is a small droplet on the surface of the mucosa. The surface is smooth, the base is wide, and multiple is common. Histologically, the polyp is formed by enlarged and regular glands. The glandular epithelial cells increase and the epithelial shrinkage is zigzag. The nucleus is arranged regularly, its size and staining. The changes in cytoplasmic content are very small, and mitotic figures are rare. According to electron microscopy, hypertrophic polyps are characterized by over-maturation of mucosal epithelial cells, and mature cells appear in the deep part of the intestinal gland. The division and proliferation of epithelial cells exceed that of surface cells. Shedding, a light imbalance that causes cell cycle renewal, so it can be considered that hyperplastic polyps are formed by excessively well-differentiated mature cells. Cell accumulation, due to the uniform structure of such polyps, the limited cell division and the full differentiation of cells, it is considered to be a non-neoplastic polyp, clinically because it is more common in older adults, and is smaller in size, so it is considered that growth is not progressive. Some people even think that such polyps may resolve on their own, hyperplastic polyps are generally not malignant, malignant transformation is only occasionally seen in mixed proliferative polyps containing adenoma components, Estrada et al reported that about 13% of proliferative polyps can contain adenomas ingredient.
(2) Lymphatic polyps: Lymphoid polyps, also known as benign lymphomas, are more common in adults aged 20 to 40 years, and slightly more males. The basic lesion is the proliferation of lymphoid follicles in the intestinal wall, which is likely the result of chronic inflammation. Not true tumors, mostly in the rectum, mostly single, can be multiple, varying in size, diameter can be from a few millimeters to 3 ~ 4cm, smooth surface or lobulated or superficial ulcer formation, most without pedicle, pedicle It is also short and thick. The histology is characterized by well-differentiated lymphoid follicular tissue, which is confined to the submucosa. The surface is covered with normal mucosa. The germinal center can be seen, often enlarged, with mitotic figures, but no mitotic division in peripheral lymphocytes. The proliferation of follicles and surrounding tissues are clearly defined, lymphatic polyps do not undergo malignant transformation, less common is benign lymphoid polyposis, the surface is a large number of lymphatic polyps, small spherical polyps of 5 ~ 6cm size, sometimes easy Misdiagnosed as familial colonic polyposis, mostly in children, histological findings are the same as single lymphoid polyps, no cancerous changes, there are reports of self-resolving, but also Road lymphoid polyposis with familial adenomatous polyposis exist of rare cases.
(3) Inflammatory polyps: Inflammatory polyps, also known as pseudopolyps, are polypoid granulomas caused by long-term chronic inflammation of the intestinal mucosa. Some people also call it fibrous epithelial polyps. This type of polyps is more common in ulcerative colitis and chronic schistosomiasis. In the intestinal tract of amebic enteritis and intestinal tuberculosis, it is often multiple, most of which are small, the diameter is often below 1cm, and the longer the course, the volume can be increased, the shape is narrower and longer, and the distal end is not wide. Regular, sometimes bridge-like, attached to the mucosa at both ends, free in the middle, histological manifestations of fibrous granulation tissue, epithelial components can be atypical hyperplasia, can be cancerous, opinions are still inconsistent, others believe that in inflammatory polyps On the basis, adenomas first develop and then become cancer.
(4) Adenomatous polyps: colorectal adenomas are benign epithelial tumors of the large intestine. Normally, the upper third of the large intestinal mucosa and the upper third of the intestinal gland are mature cells. The normal control mechanism of adenoma due to cell division has been Loss, cell division is unrestricted, mitotic activity runs through the entire length of the crypt, cells do not differentiate into mature goblet cells and absorbing cells, so immature cells can also be seen in the upper 1/3 segment and surface of the intestinal gland Mature goblet cells and absorptive cells are rare, nuclear staining is concentrated, nucleoplasm is imbalanced, mitotic figures are increased, and often with varying degrees of dysplasia. Obviously histology has tumor characteristics in colorectal polyps. In addition to hyperplastic polyps, 80% of other polyps are adenomas, which can be divided into three types according to their histological structure, namely tubular adenomas, villous adenomas and mixed adenomas.
1 tubular adenoma is a round or oval polyp with smooth or lobed surface, varying in size, 76.6% below 1cm in diameter, 80% pedicle, 10% broad-based, and the remaining 10% over-form, some Reported about 1/3 or so can be multiple, histology is the majority of tubular glands, immature cells are distributed at all levels of the gland, can have varying degrees of dysplasia, and sometimes a small number of nipple hyperplasia, tubular adenoma The incidence of invasive carcinoma is between 2% and 5%, 5% to 9% have lymph node metastasis, and pedunculated tubular adenomas less than 1 cm in diameter can have a cancer rate of less than 1%.
2 villous adenomas are rare compared with tubular adenomas, the incidence is 6:1 ~ 10:1 compared with tubular adenomas, most of them are single, generally larger, 86% of the diameter is more than 1cm, large Most are broad-based, 10% to 20% can have pedicles, the surface is dark red, rough or fluffy or small nodular, soft and brittle, can touch the activity, such as touching induration or fixation, it means Carcinogenesis may be the most common in the rectum, 80% to 85%, followed by the sigmoid colon, 10% to 13%, histologically, the epithelium is fine papillary growth, the center is the vascular connective tissue interstitial, also accompanied by epithelial hyperplasia , branch into papillary growth, epithelial cells mostly showed dysplasia, the incidence of canceration is more than 10 times larger than tubular adenoma, 10% to 60%, combined with 1049 resected villous adenomas, incidence of invasive carcinoma It is 30%.
3 mixed adenoma is an adenoma with both of the above structures, the incidence of which is different from the diagnostic criteria. It is pointed out that about 1/3 of the single tubular tumors can have different velvety components on the slice, fluff The incidence of hyperplasia is positively correlated with the volume of adenoma. Jackman's observation is a small adenoma with a diameter of less than 0.5 cm. The appearance of villus is about 0.8%, and the adenoma is 0.5 to 1 cm in diameter. The appearance of the villus component is about 11.7%, while the large adenoma with a diameter of more than 1 cm has a villus content of 43%. The carcinogen can sometimes be used in the same intestine of experimental animals when the experimental animal induces colorectal cancer. These three types of adenomas are also found in the same time. Therefore, many pathologists believe that tubular adenomas and villous adenomas are only different growth types of adenomas, rather than different lesions. Carcinogenesis of mixed adenomas occurs. The rate is between the tubular adenoma and the villous adenoma, and its biological behavior gradually approaches the villous adenoma with the increase of papillary hyperplasia.
2. The relationship between colorectal adenoma and cancer
Colorectal cancer is closely related to adenoma. Most colorectal cancers evolved from adenomas, especially villous adenomas. Generally, the tumors are larger, and the malignant rate of severe dysplasia is more than 50%. Some reports indicate that patients with colorectal adenomas have large intestines. The incidence of cancer can be 3 to 5 times higher than that of the general population, and multiple adenomas can be about 10 times higher. Because of the animal model of chemical carcinogens, adenomas and cancers can be formed simultaneously in the large intestine. It seems that both are due to the same pathogenesis. Therefore, the view that colorectal cancer is evolved from adenoma has been paid attention to. Colorectal cancer is mainly evolved from adenoma, and some colorectal cancer can also be directly derived from normal colorectal mucosa epithelium, which evolved from atypical hyperplasia. Morson believes that It takes about 10 years for an adenoma to develop into a cancer. Older women, women with a greater chance of cancer of the distal colon, but the malignant potential of each adenoma is inconsistent, so the time of canceration is also different. The cancer of adenoma is related to its size, morphology and pathological type.
1 histological type of adenoma: the incidence of invasive carcinoma of villous adenoma is 10 to 20 times larger than that of tubular adenoma, and mixed adenoma is also significantly higher than tubular adenoma, indicating that the more villus components of adenoma epithelium, malignant The greater the potential.
2 The size of adenoma: It is believed that the larger the adenoma, the higher the chance of canceration, the canceration of more than 2.0cm can reach 50%, the size of adenoma is positively correlated with carcinogenesis, and the size of adenoma is also positively correlated with the composition of villi. Polyposis cancer recognition, should pay attention to the carcinogenesis of the polyp head and base, so it can not be judged by endoscopic features alone, it is best to perform histopathological examination after electric cutting, in order to confirm the diagnosis.
3 degree of atypical hyperplasia of adenoma epithelium: the atypical hyperplasia of villous adenoma is more obvious and heavier. The atypical hyperplasia of tubular adenoma epithelium is lighter and less, and the clinical data proves mild. Atypical adenomas, about 18 years after the onset of cancer, and only 3.6 years of severe dysplasia.
4 Relationship with intestinal mucosa: Wolff reported that the incidence of invasive carcinoma of 127 cases of broad-based adenoma was 10.2%, and the incidence of invasive carcinoma of 728 cases of pedicled adenoma was 4.5%, suggesting that the malignant potential of pedicled adenoma is wider than that of broad base. The adenoma is low.
5 Shape: Segawa reported that the canceration rate of adenoma was 3.9% in the shape of smooth, 33.3% of the surface was fine-grained, and 50% of the surface was cauliflower. In general, the colorectal adenomatous polyp developed into colorectal cancer. A long-term process, during which the degree of abnormality of the colorectal adenoma, pathological type, size, number and shape are potential factors for adenoma carcinogenesis. The more abnormal the degree of abnormality, the more the villus component, the larger the volume, the more the number of pieces. The wider the base and the higher the risk of adenoma carcinogenesis, it should be removed early to stop the development of cancer.
Prevention
Elderly colon polyps prevention
Primary prevention (cause prevention): The cause of this disease is unknown, and the inflammation of the colon should be treated promptly. At the same time, attention should be paid to factors such as diet and genetics.
Secondary prevention: For patients with blood in the stool, diarrhea, difficulty in defecation, and abdominal pain, a colonoscopy should be performed in time to confirm the diagnosis as secondary prevention.
Third-level prevention: The recurrence rate of polyps is high. After treatment, colonoscopy should be reviewed regularly. If there is recurrence, timely treatment, this is a third-level prevention.
Complication
Elderly colon polyp complications Complications, intussusception, intestinal obstruction
A large number of bleeding, prolapse, intussusception, intestinal obstruction and so on.
Symptom
Colonic polyps symptoms in the elderly Common symptoms Abdominal pain, blood in the stool, constipation, dyspnea, bloating, bloating
Colorectal polyps are more common in adults over 40 years old. There are a few males, most of them have no obvious symptoms. They are accidentally found only during physical examination or autopsy. They can have the following symptoms:
1. Blood in the stool: The blood in the stool is more common in the left large intestine, especially the villous adenoma is more common, the blood is bright red, and severe cases can cause anemia.
2. Stool traits: Large intestine polyps can cause more mucus to be discharged. Sometimes polyps are multiple or large, it can also cause diarrhea or difficulty in defecation. Some large villous adenomas can have a larger amount of mucus discharge. That is, the secreted hyperthyroid adenoma can discharge more than 1 to 3 liters per day, and the discharge contains high sodium and potassium, so it can cause dehydration, low sodium, low potassium and other symptoms in the clinic. In severe cases, you can stun and die in shock.
3. Abdominal pain: relatively rare, sometimes larger polyps can cause intussusception, leading to abdominal pain caused by intestinal obstruction.
4. Polyp prolapse: a polyp with a long pedicle in the rectum can come out of the anus during defecation.
Examine
Examination of colon polyps in the elderly
1. Blood, routine examination
Intestinal polyps with chronic bleeding may have a decrease in hemoglobin, positive fecal occult blood, and sometimes a large amount of mucus.
2. Anal finger examination
Rectal polyps close to the anus can be found by anal finger examination. Generally, anal finger examination can find rectal polyps within 5cm from the anus.
3. X-ray inspection
Upper gastrointestinal polyps can be used for upper gastrointestinal tract angiography. The higher the polyps, the higher the detection rate. The polyps with a diameter of less than 1.0cm are easily missed. The detection rate is 55%-65%. The gastrointestinal barium meal is the diagnosis of the small intestine. The main method of polyps, barium enema is simple and easy to perform, it is an important method for the diagnosis of digestive tract polyps. The double angiography of barium enema has a detection rate of colon polyps above 1cm, due to the cancer rate of polyps above 1cm. 10%, 50% above 2cm, small polyps (diminutive polyp, polyps less than 5mm in diameter) have a cancer chance of only 0.1%, so barium enema is meaningful for screening for malignant polyps, due to the perforation rate of colonoscopy 1/50001/200, the mortality rate is 1/50001/2000, and the perforation rate of barium enema is 1/125001/2500, the mortality rate is 1/50,000, and the colonoscopy is about 43%. The examination can not reach the ileocecal department, the rate of missed diagnosis is similar to that of barium enema, and the price of barium enema is 1/5 to 1/3 of colonoscopy. Therefore, barium enema has its unique superiority in the diagnosis of digestive polyps. Under gas double contrast, the colon polyps appear round or oval The translucent tincture fills the defect or presents a soft tissue shadow in the inflated intestine. The polyp can be covered by the expectorant according to its size. When the local compression is applied, the filling defect can be seen (simple barium angiography) or visible from the side. To the polyp shadow (the double contrast of hernia), the sessile polyps can be seen with round or oval filling defects, and pedicles can be seen in different lengths.
4. Endoscopy
Fiber endoscopy or electron endoscopy is the most accurate and reliable method for the diagnosis of intestinal polyps. Due to the larger magnification of the electronic endoscope, the rate of missed diagnosis of small polyps is significantly reduced. The advantage of endoscopy is that biopsy can be performed on polyps. There is no false positive, colon endoscopy should strive to reach the ileocecal department to avoid missed examination, and the examination should be carefully avoided to avoid small polyps, because about 1/3 of the lower digestive tract polyps are multiple, so not in the colonoscopy Should be satisfied with the discovery of a polyp, should be carefully examined throughout the colon, for each of the polyps found greater than 1cm should be multi-site biopsy to determine its nature.
Diagnosis
Diagnosis and diagnosis of colon polyps in the elderly
diagnosis
Most colorectal polyps have no special symptoms, so the diagnosis depends mainly on clinical examination. The examination steps are generally simple and deep. First, digital rectal examination and rectal sigmoidoscopy are performed. Generally, polyps within 25 cm from the anus can be found and can be visually observed. Biopsy, X-ray barium enema examination and fiberoptic colonoscopy on polyps more than 25cm in the anus. Since a large intestine adenoma is found, about 1/3 of cases can have a second adenoma, so most people advocate Sigmoidoscopy should be performed when the adenoma is found. X-ray barium enema and fiberoptic colonoscopy have their own advantages and disadvantages. Barium enema examination is easier, patients are more tolerable, and complications are less, but even Gastric double contrast angiography is also easy to miss diagnosis of small polyps than fiberoptic colonoscopy, and can not be biopsied. If the polyps are found to be broad-based, or the diameter is greater than 2cm, or the surface is ulcerated or infiltrated At the time, it should be highly suspected of malignancy, and a fiber colonoscopy should be performed.
Differential diagnosis
Must be differentiated from adenomas, malignant polyps, hyperplastic polyps, juvenile polyps, inflammatory polyps, lymphoid polyps and deep cystic colitis.
