Location and appearance of two example colorectal tumors
Endoscopic image of a colon affected by ulcerative colitis. The internal surface of the colon is blotchy and broken in places. Mild-moderate disease.
Longitudinally opened freshly resected colon segment showing a cancer and four polyps. Plus a schematic diagram indicating a likely field defect (a region of tissue that precedes and predisposes to the development of cancer) in this colon segment. The diagram indicates sub-clones and sub-sub-clones that were precursors to the tumors.
Classification of colitis, often used in defining the extent of involvement of ulcerative colitis, with proctitis (blue), proctosigmoiditis (yellow), left sided colitis (orange) and pancolitis (red). All classes extend distally to the end of the rectum.
Colon cancer with extensive metastases to the liver
Gross pathology of normal colon (left) and severe ulcerative colitis (right), forming pseudopolyps (smaller than the cobblestoning typically seen in Crohn's disease), over a continuous area (rather than skip lesions of Crohn's disease), and with a relatively gradual transition from normal colon (while Crohn's is typically more abrupt).
Relative incidence of various histopathological types of colorectal cancer. The vast majority of colorectal cancers are adenocarcinomas.
Aphthous ulcers involving the tongue, lips, palate, and pharynx.
Micrograph of colorectal adenocarcinoma, showing "dirty necrosis".
Pyoderma gangrenosum with large ulcerations affecting the back.
A diagram of a local resection of early stage colon cancer
Endoscopic image of ulcerative colitis affecting the left side of the colon. The image shows confluent superficial ulceration and loss of mucosal architecture. Crohn's disease may be similar in appearance, a fact that can make diagnosing UC a challenge.
A diagram of local surgery for rectal cancer
H&E stain of a colonic biopsy showing a crypt abscess, a classic finding in ulcerative colitis
Colon and rectum cancer deaths per million persons in 2012
Colonic pseudopolyps of a person with intractable UC, colectomy specimen
Biopsy sample (H&E stain) that demonstrates marked lymphocytic infiltration (blue/purple) of the intestinal mucosa and architectural distortion of the crypts.

Another risk factor is inflammatory bowel disease, which includes Crohn's disease and ulcerative colitis.

- Colorectal cancer

Complications may include abnormal dilation of the colon (megacolon), inflammation of the eye, joints, or liver, and colon cancer.

- Ulcerative colitis
Location and appearance of two example colorectal tumors

6 related topics

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The three most common sites of intestinal involvement in Crohn's disease (left) compared to the areas affected by colitis ulcerosa (right).

Crohn's disease

Type of inflammatory bowel disease that may affect any segment of the gastrointestinal tract.

Type of inflammatory bowel disease that may affect any segment of the gastrointestinal tract.

The three most common sites of intestinal involvement in Crohn's disease (left) compared to the areas affected by colitis ulcerosa (right).
An aphthous ulcer on the mucous membrane of the mouth in Crohn's disease.
A single lesion of erythema nodosum
Endoscopic image of colon cancer identified in the sigmoid colon on screening colonoscopy for Crohn's disease
NOD2 protein model with schematic diagram. Two N-terminal CARD domains (red) connected via helical linker (blue) with central NBD domain (green). At C-terminus LRR domain (cyan) is located. Additionally, some mutations which are associated with certain disease patterns in Crohn's disease are marked in red wire representation.
Distribution of gastrointestinal Crohn's disease.
Endoscopic image of Crohn's colitis showing deep ulceration
CT scan showing Crohn's disease in the fundus of the stomach
Endoscopic biopsy showing granulomatous inflammation of the colon in a case of Crohn's disease.
Section of colectomy showing transmural inflammation
Resected ileum from a person with Crohn's disease

Bowel obstruction may occur as a complication of chronic inflammation, and those with the disease are at greater risk of colon cancer and small bowel cancer.

Because of the 'patchy' nature of the gastrointestinal disease and the depth of tissue involvement, initial symptoms can be more subtle than those of ulcerative colitis.

Colonoscopy being performed

Colonoscopy

Endoscopic examination of the large bowel and the distal part of the small bowel with a CCD camera or a fiber optic camera on a flexible tube passed through the anus.

Endoscopic examination of the large bowel and the distal part of the small bowel with a CCD camera or a fiber optic camera on a flexible tube passed through the anus.

Colonoscopy being performed
A container of PEG (polyethylene glycol or macrogol) with electrolyte used to clean out the intestines before certain bowel exam procedures such as a colonoscopy.
Schematic overview of colonoscopy procedure
Polyp is identified.
A sterile solution is injected under the polyp to lift it away from deeper tissues.
A portion of the polyp is now removed.
The polyp is fully removed.

It can provide a visual diagnosis (e.g., ulceration, polyps) and grants the opportunity for biopsy or removal of suspected colorectal cancer lesions.

In most cases the positive result is just due to hemorrhoids; however, it can also be due to diverticulosis, inflammatory bowel disease (Crohn's disease, ulcerative colitis), colon cancer, or polyps.

Micrograph showing inflammation of the large bowel in a case of inflammatory bowel disease. Colonic biopsy. H&E stain.

Inflammatory bowel disease

Micrograph showing inflammation of the large bowel in a case of inflammatory bowel disease. Colonic biopsy. H&E stain.
Associated loci pane. Pink genes are in IBD associated loci, blue are not.

Inflammatory bowel disease (IBD) is a group of inflammatory conditions of the colon and small intestine, Crohn's disease and ulcerative colitis being the principal types.

Many studies identified that microRNAs dysregulation involved in IBD and to promote colorectal cancer.

Micrograph of the small intestine mucosa showing the intestinal glands - bottom 1/3 of image. H&E stain.

Intestinal gland

Intestinal gland is a gland found in between villi in the intestinal epithelium lining of the small intestine and large intestine (or colon).

Intestinal gland is a gland found in between villi in the intestinal epithelium lining of the small intestine and large intestine (or colon).

Micrograph of the small intestine mucosa showing the intestinal glands - bottom 1/3 of image. H&E stain.
Colonic crypts (intestinal glands) within four tissue sections. In panel A, the bar shows 100 µm and allows an estimate of the frequency of crypts in the colonic epithelium. Panel B includes three crypts in cross-section, each with one segment deficient for CCOI expression and at least one crypt, on the right side, undergoing fission into two crypts. Panel C shows, on the left side, a crypt fissioning into two crypts. Panel D shows typical small clusters of two and three CCOI deficient crypts (the bar shows 50 µm). The images were made from original photomicrographs, but panels A, B and D were also included in an article
Micrograph showing intestinal crypt branching, a histopathological finding of chronic colitides. H&E stain.
Micrograph showing crypt inflammation. H&E stain.

Loss of proliferation control in the crypts is thought to lead to colorectal cancer.

inflammatory bowel disease (e.g. ulcerative colitis, Crohn's disease),

Scheme of digestive tract, with rectum marked

Rectum

Final straight portion of the large intestine in humans and some other mammals, and the gut in others.

Final straight portion of the large intestine in humans and some other mammals, and the gut in others.

Scheme of digestive tract, with rectum marked
The inside of a normal human rectum in a 70-year-old, seen during colonoscopy
Retroflexed view of the human rectum seen at colonoscopy showing anal verge
A digital rectal exam is conducted to investigate or diagnose conditions including of the prostate.
Arteries of the pelvis
Blood vessels of the rectum and anus
Cross-section microscopic shot of the rectal wall
Dog rectum cross-section (40×)
Microscopic cross-section of the rectum of a dog (400×), showing a high concentration of goblet cells in amongst the column-shaped lining. Goblet cells can be seen as the circular cells with a clear inner material (cytoplasm).

Ulcerative colitis, one form of inflammatory bowel disease that causes ulcers that affect the rectum. This may be episodic, over a person's lifetime. These may cause blood to be visible in the stool. the cause is unknown.

Rectal cancer, a subgroup of colorectal cancer specific to the rectum.

Micrograph of pseudomembranous colitis, an indication for colectomy. H&E stain.

Colectomy

Bowel resection of the large bowel (colon).

Bowel resection of the large bowel (colon).

Micrograph of pseudomembranous colitis, an indication for colectomy. H&E stain.

Colon cancer

Inflammatory bowel disease such as ulcerative colitis or Crohn's disease. Colectomy neither cures nor eliminates Crohn's disease, instead only removing part of the entire diseased large intestine. A colectomy is considered a "cure" for ulcerative colitis because the disease attacks only the large intestine and therefore will not be able to flare up again if the entire large intestine (cecum, ascending colon, transverse colon, descending colon and sigmoid colon) and rectum are removed. However, it does not always take away extra-intestinal symptoms.