Background of Crohn's Disease
Crohn's disease is an idiopathic, chronic inflammatory process of the digestive tract, belonging, with ulcerative colitis, to the inflammatory bowel disease family. It is a patchy, transmural illness that can affect any part of the gastrointestinal tract from the mouth to the anus. However, in most cases it is localized at the terminal ileum, the colon, and/or the perianal region.
Often the inflammatory patches are surrounded by healthy tissue, and can spread deeper into the tissues.
Histopathy
Macroscopically, hyperemia, edema and ulcerations characterize the involved mucosa. The ulcerations can become deep and serpiginous, located transversely and longitudinally over an inflamed mucosa, giving the mucosa a cobblestone appearance. Segments of affected mucosa alternates with healthy areas (skip lesions).
Microscopically there are focal inflammatory infiltrates around the crypts and ulcerations of superficial mucosa. These organize into noncaseating granulomas.
Unlike Crohn's disease, ulcerative colitis is limited to the mucosa and submucosa of the large intestine or rectum. Most commonly the disease begins distally and extends proximally. The affected segment of intestine is continuous.
Characterized by Periods of Flare up and Remissions
Clinically, both Crohn's disease and ulcerative colitis are an alternation of remission, asymptomatic phases, and of acute relapses (active disease phases). The relapses are characterized by general and intestinal disabling symptoms (abdominal pain and cramping, fatigue, weight loss, fever, diarrhea, gastrointestinal bleeding, recurrent subocclusive episodes, complete obstruction requiring surgery, etc.), resulting in alteration of quality of life and/or repeated hospitalization.
Complications
Crohn's disease may lead to one or more of the following complications:
- Bowel obstruction. Crohn's disease affects the entire thickness of the intestinal wall. Over time, parts of the bowel can thicken and narrow, which may block the flow of digestive contents through the affected part of your intestine. Some cases require surgery to remove the diseased portion of your bowel.
- Ulcers. Chronic inflammation can lead to open sores (ulcers) anywhere in your digestive tract, including your mouth and anus, and in the genital area (perineum) and anus.
- Fistulas. Sometimes ulcers can extend completely through the intestinal wall, creating a fistula - an abnormal connection between different parts of your intestine, between your intestine and skin, or between your intestine and another organ, such as the bladder or vagina. When internal fistulas develop, food may bypass areas of the bowel that are necessary for absorption. An external fistula can cause continuous drainage of bowel contents to your skin, and in some cases, a fistula may become infected and form an abscess, a problem that can be life-threatening if left untreated.
- Anal fissure. This is a crack, or cleft, in the anus or in the skin around the anus where infections can occur. It's often associated with painful bowel movements.
- Malnutrition. Diarrhea, abdominal pain and cramping may make it difficult for you to eat or for your intestine to absorb enough nutrients to keep you nourished. Additionally, anemia is common in people with Crohn's disease.
- Other health problems. In addition to inflammation and ulcers in the digestive tract, Crohn's disease can cause problems in other parts of the body, such as arthritis, inflammation of the eyes or skin, clubbing of the fingernails, kidney stones, gallstones and, occasionally, inflammation of the bile ducts. People with long-standing Crohn's disease also may develop osteoporosis, a condition that causes weak, brittle bones.