Colon melanosis

Introduction Colorectal melanosis is a non-inflammatory, benign, reversible disease characterized by pigmentation of the large intestine. Named because the large intestine mucosa is tan or black under the endoscope. Clinical manifestations such as secret and abdominal pain or abdominal discomfort are the main manifestations. Due to the retention of food residues caused by chronic obstruction, the proteolytic products become pigment particles deposited in the intestinal mucosa under the action of enzymes, which are related to chronic colonic obstruction; or the pigment particles or colonic excretion pigment particles synthesized by intestinal bacteria are absorbed by the colon. Due to decreased ability; or due to stimulation of resinous substances in laxatives, causing intestinal epithelial cell damage; or the presence of abnormal enzymes in the submucosal plexus, laxatives activate the activity of these enzymes, thereby accumulating pigments, nerves Caused by dysfunction, etc.

Cause

The pathogenesis of colorectal melanosis is still unclear. The main generalizations are:

(1) The theory of detention, that is, related to chronic colonic obstruction, due to the retention of food residues caused by chronic obstruction, the protein breakdown products become pigment particles deposited on the intestinal mucosa under the action of enzymes.

(2) Absorption theory, that is, the ability of the colon to absorb pigment particles synthesized by intestinal bacteria or colonic pigment particles.

(3) Stimulation theory, that is, due to the stimulation of resinous substances in the laxative, the pigment particles are synthesized in the large intestine and then settled in the lamina propria of the intestine, which is caused by phagocytosis by phagocytic cells.

(4) Injury theory, that is, laxatives cause damage to intestinal epithelial cells, which are phagocytosed by phagocytic cells in the lamina propria, and the pigmented cells in these large cytoplasms make the intestinal mucosa appear black.

(5) Enzyme abnormality theory, that is, the presence of abnormal enzymes in the intestinal submucosal plexus of some people, the laxative activates the activity of these enzymes, thereby accumulating pigments, neurological disorders and the like.

an examination

Related inspection

Gastrointestinal CT examination of gastrointestinal diseases by ultrasonography

It is a method of examining the colonic lesion from the mucosal side by inserting the enteroscopy into the ileocecal region through the anus. It is the best choice for the diagnosis of mucosal lesions of the large intestine. It transmits the image of the colonic mucosa to the computer processing center through an electronic camera probe installed at the front end of the enteroscopy, and then displays it on the monitor screen to observe the tiny mucous membrane of the large intestine. Variety.

Differential diagnosis

The disease should be distinguished from brown intestinal syndrome, which is found in adult patients with celiac disease and vitamin E deficiency. Lipid brown pigment is deposited around the nucleus of intestinal smooth muscle cells, making the small intestine and colon look completely tan, but the colonic mucosa may be absent. Pigmentation, pathological manifestations of colonic mucosal epithelial cells are generally normal, submucosal thickening edema, the lamina propria have a number of mononuclear phagocytic cells containing pigment particles, some scattered, and some clusters appear.

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