Colon polyps

Introduction Broadly speaking, any bulging lesion that protrudes from the lumen of the intestine can be called a polyp, but the polyps that are generally referred to are only mucosal localized bulges. The name polyp has no histological meaning and cannot be confused with adenoma. It should be said that polyps are a benign lesion, not a cancer, and will not endanger life. The histological types of polyps are: adenoma, hamartoma, inflammatory and hyperplastic. Colonic polyps are predominantly in the rectum and sigmoid colon.

Cause

Causes:

Infection

It has been reported that the occurrence of adenomatous polyps is related to viral infections;

2. Age

The incidence of colon polyps increases with age;

3. Embryonic abnormalities

Juvenile polyposis is mostly hamartoma, which may be related to abnormal embryonic development;

4. Lifestyle

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;

5. Genetics

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 this allele is mutated, an adenoma occurs at the site of the mutation. This mutation is called a somatic mutation.

an examination

In addition to juvenile polyps are more common in children under the age of 12, especially children under the age of 5, the rest of the colon polyps are more common in adults over 40 years old, a little more men. Most cases have no noticeable symptoms.

1. Rectal examination can touch low polyps.

2. Anoscope, straight B-ray or fiberoptic colonoscopy can be seen directly to see polyps.

3. Barium enema can show filling defects.

Differential diagnosis

Various polyps characteristics:

1. Juvenile polyps: About 90% occur in children under the age of 10, which is more common in boys. The appearance is round or oval and the surface is smooth. 90% grow in the range of 25 cm from the anus, most of them are less than 1 cm in diameter, most of them have pedicles, about 25% are multiple, histologically manifested as well-differentiated and irregularly shaped glands, and some form capsules. Sexual expansion, medium storage mucus, interstitial hyperplasia, and more inflammatory cell infiltration, sometimes ulceration on the surface. Subspecies polyps generally do not undergo malignant transformation.

2, hyperplastic polyps: hyperplastic polyps are the most common type of polyps, also known as metaplastic polyps. The distribution is mostly in the distal large intestine, generally small, and the diameter is rarely more than 1 cm. Its shape is a droplet-shaped protrusion on the surface of the mucosa. The surface is smooth, the base is wide, and multiple is common. The last time of histology Polyps are formed by enlarged and regular glands. The glandular epithelial cells increase and the skin shrinks into a zigzag shape. The nucleus is arranged regularly, and its size and chromatin content change little. The mitotic phase is rare. Its important feature is that mature cells appear in the middle and lower parts of the intestinal crypt. Proliferative polyps do not undergo malignant transformation.

3, lymphatic polyps: lymphoid polyps, also known as benign lymphoma, more common in adults aged 20 to 40 years old, can also occur in children, slightly more males, more in the rectum, especially in the lower rectum, mostly single or multiple , ranging in size, from a few millimeters to 3 to 4 centimeters in diameter. The surface is smooth or lobulated or has superficial ulceration. Most of them are pedunculated, and they are short and thick when they are pedicled. Histologically, it is a well-differentiated lymphoid follicular tissue that is confined to the submucosa and covers the normal mucosa. It can be seen that the germinal center is often enlarged and has a mitotic image, but there is no nuclear division in the surrounding lymphocytes, and the proliferating follicles are clearly separated from the surrounding tissues. Lymphatic polyps do not develop cancer. Less common is benign lymphoid polyposis. Expressed as a large number of lymphatic polyps. Small spherical polyps of 5-6 cm, mostly in children. Histology changes to lymphatic polyps.

4, inflammatory polyps: inflammatory polyps, also known as pseudopolyps, is a polypoid granuloma caused by long-term chronic inflammation of the intestinal mucosa, this polyp is more common in ulcerative colitis, chronic schistosomiasis, amoebic dysentery and intestinal tuberculosis The lesion is in the intestine. Often multiple, most of them are small, the diameter is often less than 1 cm, and the longer the course, the volume can be increased. The shape is narrow, long, wide and irregular at the far end. Sometimes it is bridge-like, with both ends attached to the mucosa and the middle part free. Histological manifestations of fibrous granulation tissue, epithelial components can also be mesenchymal changes, is not certain.

5, adenoma: colon adenoma is a benign epithelial tumor of the large intestine. According to the histological structure, it is divided into three types: tubular adenoma, villous adenoma and mixed adenoma.

(1) Tubular adenoma: a round or elliptical polyp with a smooth surface or lobes, varying in size, but most of which are less than 1 cm in diameter. 80% have pedicles. Histology is expressed in most tubular glandular glands, and immature cells are distributed at all levels of the gland. There may be varying degrees of mesenchymal changes, and sometimes a small number of nipple hyperplasia. Its cancer rate is about 1% to 5%.

(2) villous adenoma: less common than tubular adenoma, the vast majority are single. Generally, the volume is large, and the diameter is mostly more than 1 cm. Most of them are broad-based, and about 10-20% can have pedicle. The surface is dark red, rough or villous or small nodular, soft and brittle, can touch the activity, such as touching induration or fixation, it indicates that there is cancer. The distribution is most in the rectum, followed by the sigmoid colon. Histological manifestations of epithelial papillary growth, the center of the vascular connective tissue interstitial, accompanied by epithelial hyperplasia, divided into papillary growth, epithelial cells become more obvious. Its cancerous rate is more than 10 times larger than tubular adenoma.

(3) Mixed adenoma: an adenoma having both of the above structures. Its cancer rate is between tubular adenoma and villous adenoma.

6, familial colon polyps. Familial colonic polypemia is attributed to adenomatous polyp syndrome. It is an autosomal dominant hereditary disease. Occasionally, there is no family history. There are multiple adenomas in the whole colon and rectum. Most adenomas have pedicles and nipples. The shape is less common, the number of polyps varies from about 100 to thousands, ranging from the size of soybeans to several centimeters in diameter, often densely arranged, sometimes in strings, and its tissue structure is no different from general adenomas. In addition to juvenile polyps are more common in children under the age of 12, especially children under the age of 5, the rest of the colon polyps are more common in adults over 40 years old, a little more men. Most cases have no noticeable symptoms. Occasionally, only in physical examination or autopsy, some cases may have one or more of the following symptoms.

Blood in the stool: The blood in the stool is more common in the colon on the left side of the colon. Especially the villous adenoma and juvenile polyps are more common, often bright red, and sometimes even cause anemia. Painless bloody stools in childhood, most common in colon polyps. Fecal changes: large intestine polyps can cause more mucus discharge, sometimes polyps are multiple or larger, can also cause diarrhea or difficulty in defecation. Some large villous adenomas can have a large amount of mucus secretion, and the mucus discharged per day can reach more than 1~3 liters. The sodium and potassium content in the effluent is very high, so it can cause water loss and low chlorine in the clinic. Symptoms of low potassium and low sodium can be coma in severe cases, shock or even death. Abdominal pain: relatively rare, sometimes larger polyps can cause intussusception, resulting in intestinal obstruction and abdominal pain. Polyp prolapse: polyps with long pedicles in the rectum can be removed from the anus during defecation. This symptom is more common in children.

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