Colon melanosis

Introduction to colonic melanosis Melanosiscoli (MC) is a non-inflammatory bowel disease characterized by melanin deposition in the colonic mucosa. Its essence is that macrophages in the lamina propria of the colon mucosa contain a large amount of lipofuscin, which has been reported in foreign countries. Less, colonic melanosis has shown a clear upward trend in China in recent years. There are different degrees of pigmentation on the normal mucosa of the colon. It is brown, brown, black striped or tiger skin-like or diffuse. The polypoid is pink or white, and the submucosal vascular network is unclear. Microscopic colonic mucosal epithelial cells are generally normal, submucosal thickening edema, a large number of dense or scattered macrophages in the lamina propria, irregular morphology, cytoplasm filled with pigment particles, the nucleus is covered (Figure 1), sometimes giant Pigment particles can also be seen outside the phagocytes. In patients with severe colonic melanosis, macrophages and pigment granules containing pigment particles can also be seen in submucosal or mesenteric lymph nodes, when melanin staining (Fontana silver staining) is positive. Iron staining was negative. The number and volume of macrophages in the lamina propria were significantly increased under electron microscope. There was a large amount of lipofuscin in the cytoplasm and surrounding connective tissue, which was near the unmyelinated nerve fibers of the intestinal plexus. Macrophages containing lipofuscin particles were also observed, and phagocytosis of fibroblasts was also observed. basic knowledge The proportion of illness: 0.005% Susceptible people: common in the elderly Mode of infection: non-infectious Complications: colorectal cancer colon cancer rectal polyps

Cause of colonic melanosis

(1) Causes of the disease

Colonic melanosis is not hereditary and is common in the elderly. The exact cause is still unclear. As early as 1928, Banle proposed the relationship between MC and sputum laxatives (73%). Long-term oral laxatives are recognized by most scholars. The main reason for MC is that the scorpion drugs (buckthorn skin, senna leaf, rhubarb soda, etc.) are mainly used for oral administration of extracts such as Niuhuang Jiedu Tablet, Ma Ren Run Chang Pill, Aloe Vera and Fruit Guide. Laxatives and diphenylmethane laxatives (such as bisacodyl) can also cause MC, and the time and method of taking the drug also affect the occurrence of MC. It is reported that the shortest time for colonic melanosis in patients taking laxatives is 4 abroad. In the month, the domestic was 1 month, and the rate was 23.0% in less than 4 months. The other group showed that the incidence of colonic melanosis was 9.52% in patients with intermittent medication for less than 1 year, and 11.25 for intermittent medication for more than 1 year. %, continuous medication for less than 1 year, the incidence of MC is 77.78%; the incidence of continuous medication for more than 1 year, the incidence rate is as high as 81.06%, however, not all MC are related to laxatives, about 1/4 of patients take long-term use There is no blackening in the laxative, and there is no long-term in the l/4 blackening patient. History of medication, patients with constipation reduction, MC reduced or disappeared, that constipation may be one of the reasons, in recent years, as people's eating habits change, that is, fat and protein intake increased, cellulose intake decreased, constipation, rectum Prominence, anorectal reflex disorder and other patients with defecation difficulties, colonic melanosis patients significantly increased, ulcerative colitis may also be another factor leading to MC, some patients have not used laxatives and endoscopy but also found ulcers Patients with colitis and melanosis, as well as some patients with chronic diarrhea, have MC at the same time. It is concluded that chronic diarrhea is also one of the causes of MC. It has been reported that the ureter and colon are consistent after the gunshot wound in the abdomen, and the blackening occurs below the anastomosis. In addition, some people think that old and weak, gastrointestinal dysfunction, feces in the intestinal tract for too long may also be related to MC, there are people who also propose that age also affects the occurrence of MC, of which the incidence of >60 years is significantly higher than other In the age group (P<0.01), the incidence rate was as high as 88%. As for the relationship between MC and colorectal cancer and adenoma, polyps, the literature reports are inconsistent. The concomitant rate of colon cancer was 5.4% and 5.9%, respectively, and the rate of colon polyps was 55% and 19.2%, respectively. Prospective studies of Siegers showed that MC had an increased risk of colorectal cancer, Tanaka et al. Hydroxyanthrene successfully established an animal model of colorectal tumors. A domestic dataset suggested that the incidence of colon polyps in MC patients was 36%. A summary of 14 retrospective studies indicated that taking steroids and other laxatives The relationship with colorectal cancer was statistically significant, but a case-control study by Nusko et al showed that taking sputum laxatives did not increase the risk of colon adenomas and colon cancers due to Colon polyps are clear precancerous lesions. Although it is still unclear whether colon tumors are associated with MC or the causal relationship, it is necessary to be aware of colon cancer after MC is involved. In short, MC is a kind of long-term constipation and It is unclear about the pigmentation of laxative-related pigmentation diseases. The phenomenon of colonic melanosis is caused by constipation itself, or by the long-term use of stimulating laxatives, or a combination of both factors. Pending further prospective studies fruit, and a clear relationship between colon cancer, colon (villous) adenomas and ulcerative colitis.

(two) pathogenesis

The various pigments contained in laxatives are the underlying cause of the disease, and Isek reported that MC occurred in a patient who took 7-year-old bamboo leaf extract, as evidenced by this.

After entering the large intestine, various laxatives can cause transient, dose-related apoptosis of colonic mucosal epithelial cells. The resulting apoptotic bodies are engulfed by mononuclear macrophages and migrate through the basement membrane pores to the lamina propria of the mucosa. In the lysosome of macrophages, apoptotic bodies are transformed into typical lipofuscin or other pigments. With the long-term application of laxatives, these pigment-containing macrophages continue to aggregate and eventually develop into typical MC changes. Due to the massive accumulation of lipofuscin particles in macrophages, the cells are disintegrated in severe cases, and the lipofuscin particles gradually diffuse into the surrounding connective tissue interstitial. This phenomenon can be found by electron microscopy, which is currently recognized by most scholars. The pathogenesis of MC, histochemical studies show that MC pigment contains glycolipid and glycoprotein components, supports the origin of apoptotic epithelial cells or their metabolites, rather than the laxative itself, and the number of apoptotic epithelial cells is positively correlated with the degree of MC. Of course, some people have suggested that apoptosis is not necessarily the main mechanism for MC.

There are different degrees of pigmentation on the normal mucosa of the colon. It is brown, brown, black striped or tiger skin-like or diffuse. The polypoid is pink or white, and the submucosal vascular network is unclear. Microscopic colonic mucosal epithelial cells are generally normal, submucosal thickening edema, a large number of dense or scattered macrophages in the lamina propria, irregular morphology, cytoplasm filled with pigment particles, the nucleus is covered (Figure 1), sometimes giant Pigment particles can also be seen outside the phagocytes. In patients with severe colonic melanosis, macrophages and pigment granules containing pigment particles can also be seen in submucosal or mesenteric lymph nodes, when melanin staining (Fontana silver staining) is positive. Iron staining was negative. The number and volume of macrophages in the lamina propria were significantly increased under electron microscope. There was a large amount of lipofuscin in the cytoplasm and surrounding connective tissue, which was near the unmyelinated nerve fibers of the intestinal plexus. Macrophages containing lipofuscin particles were also observed, and phagocytosis of fibroblasts was also observed.

Prevention of colonic melanosis

1, establish a good bowel habit

Usually develop the habit of regular bowel movements. Focus on your bowel movements, don't read newspapers or do other things.

2, more intake of dietary fiber

Dietary fiber-rich foods include wheat bran or brown rice, vegetables such as celery, leeks, etc., to increase the amount of water to enhance the stimulation of the colon.

3, to increase the amount of exercise

So in the morning, you can walk, jog, and do gymnastics. If you don't have time, you can do more than half a squat in the office, or you can exercise your abdominal muscles to make up for lack of exercise.

4, good mental state

To adjust your emotional and psychological state, occasionally a constipation does not have a psychological burden.

5, the correct treatment

The safest and most effective drug for the treatment of constipation is Shutaiqing polyethylene glycol electrolyte powder. For more stubborn constipation, you should seek the help of a specialist to check the cause of constipation, and use comprehensive treatment according to the severity and type of constipation.

6, the intestines must have a way

Intestinal clearing is required to clean the whole intestine without causing harm to the body (such as abdominal pain, dependence, colonic blackening, etc.). The method of clearing the intestines includes food clearing the intestines, Shutaiqing physical intestines, and saline intestines.

Complications of colonic melanosis Complications colorectal cancer colon cancer rectal polyps

Relationship with tumors: Patients with colonic melanosis have a higher incidence of colorectal cancer. Morgenstern counts 511 cases of colorectal cancer resection specimens, 5.9% with melanosis, Zhao Dongli et al reported 38 cases of MC with colon cancer in 2 cases. There were 3 cases of colon adenomatous polyps, 1 case of rectal polyps and 2 cases of postoperative colon cancer. The cause of cancer and polyps in patients with colonic melanosis may be related to the intestinal mucosa of laxative and MC pigmentation damage. Studies have shown that certain active ingredients in natural or synthetic laxatives have potential genetic toxins and carcinogenicity.

Symptoms of colonic melanosis Common symptoms Constipation hypokalemia, colonic black, abdominal distension, intestinal stenosis

Conclusions, rectal melanosis has no specific symptoms and signs, mainly abdominal distension, constipation and difficulty in defecation, a small number of patients have lower abdominal pain and poor appetite, may be related to melanosis invading the colonic plexus, resulting in intramucosal plexus Degenerative changes, leading to intestinal dysfunction and electrolyte imbalance, a small number of patients have hypokalemia, hyponatremia, hypocalcemia, occasionally edematous colon stenosis, it has been reported that this disease is more associated with colon cancer, adenoma and polyps .

Examination of colonic melanosis

Blood routine examination is normal, a small number of patients may have low sodium, low potassium, low calcium.

Colonoscopy: Endoscopic manifestations of colonic melanosis show that the colonic mucosa is smooth and intact, with light brown, tan or black pigmentation, streaky, patchy, tiger-like changes, network-like discontinuities Or continuous distribution, the intestinal lumen is significantly darker (Figure 2), may be accompanied by white or pink polyp bulge, individual cases of mucosa without significant coloration, and polyp biopsy in the sigmoid colon accidentally confirmed MC, according to the degree of intestinal mucosal pigmentation, MC is divided into III degrees: I degree, light black, similar to leopard skin, mucosal vascular texture is faintly visible, lesions are more limited, and the boundary between normal mucosa is not very clear, II degree, dark brown, with lines between dark dark brown mucosa Milky white mucosa, more common in the left colon or a segment of the colonic mucosa, the mucosal blood vessels are unclear, and the normal mucosa has a clear boundary, III degree, dark dark brown, with fine milky white lines or spots between the dark dark brown mucosa Mucosa, submucosal blood vessels are invisible, this performance is more common in the whole colon type, from the point of view of the lesion, such as lesion limitations are more common in the proximal colon, severe Can affect the whole colon, the statistics of 261 cases of MC in China, the left colon is about 32.84%, the right colon is 11.94%, the transverse colon is 26.87%, and the whole colon is 28.36%, in the liver, spleen, and B. The junction and the anastomosis are more obvious.

Diagnosis and differentiation of colonic melanosis

Mainly according to the intestinal mucosa of the intestinal mucosa have different degrees of pigmentation, histopathological examination found that there are a large number of macrophages containing pigment particles in the lamina propria of the mucosa, melanin staining is positive, and iron staining is negative, clinical manifestations can not be used as a basis for diagnosis.

The disease should be differentiated from brown intestinal syndrome, which is mainly seen in patients with steatorrhea. The essence is that lipofuscin is deposited around the nucleus of intestinal smooth muscle cells, making the colon wall brown, while the colon mucosa is non-pigmented, colon black. Patients with schizophrenia should also be differentiated from hemorrhagic colitis and submucosal blepharospasm. The latter two lesions are more limited, and the mucosa of the lesion is purple-red or bloody on the mucosal surface, while MC is a brown or black pigment of the intestinal mucosa. Calm, individual colon cancer patients have colonic mucosal hyperpigmentation, if the patient has no history of constipation and long-term El laxative, and the colonic mucosa is pigmented, should be highly alert to colon cancer.

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