Crohn's disease
Crohn's disease is a type of inflammatory bowel disease that may affect any segment of the gastrointestinal tract. Symptoms often include abdominal pain, diarrhea, fever, abdominal distension, and weight loss. Complications outside of the gastrointestinal tract may include anemia, skin rashes, arthritis, inflammation of the eye, and fatigue. The skin rashes may be due to infections, as well as pyoderma gangrenosum or erythema nodosum. Bowel obstruction may occur as a complication of chronic inflammation, and those with the disease are at much greater risk of colorectal cancer and small bowel cancer.
Although the precise causes of Crohn's disease are unknown, it is believed to be caused by a combination of environmental, immune, and bacterial factors in genetically susceptible individuals. It results in a chronic inflammatory disorder, in which the body's immune system defends the gastrointestinal tract, possibly targeting microbial antigens. Although Crohn's is an immune-related disease, it does not seem to be an autoimmune disease. The exact underlying immune problem is not clear; however, it may be an immunodeficiency state.
About half of the overall risk is related to genetics, with more than 70 genes involved. Tobacco smokers are three times as likely to develop Crohn's disease as non-smokers. Crohn's disease is often triggered after a gastroenteritis episode. Other conditions with similar symptoms include irritable bowel syndrome and Behçet's disease.
There is no known cure for Crohn's disease. Treatment options are intended to help with symptoms, maintain remission, and prevent relapse. In those newly diagnosed, a corticosteroid may be used for a brief period of time to improve symptoms rapidly, alongside another medication such as either methotrexate or a thiopurine to prevent recurrence. Cessation of smoking is recommended for people with Crohn's disease. One in five people with the disease is admitted to the hospital each year, and half of those with the disease will require surgery at some time during a ten-year period. Surgery is kept to a minimum whenever possible, but it is sometimes essential for treating abscesses, certain bowel obstructions, and cancers. Checking for bowel cancer via colonoscopy is recommended every 1-3 years, starting eight years after the disease has begun.
Crohn's disease affects about 3.2 per 1,000 people in Europe and North America; it is less common in Asia and Africa. It has historically been more common in the developed world. Rates have, however, been increasing, particularly in the developing world, since the 1970s. Inflammatory bowel disease resulted in 47,400 deaths in 2015, and those with Crohn's disease have a slightly reduced life expectancy. Onset of Crohn's disease tends to start in adolescence and young adulthood, though it can occur at any age. Males and females are affected roughly equally.
Name controversy
The disease was named after gastroenterologist Burrill Bernard Crohn, who in 1932, together with Leon Ginzburg and Gordon D. Oppenheimer at Mount Sinai Hospital in New York, described a series of people with inflammation of the terminal ileum of the small intestine, the area most commonly affected by the illness. The decision to name the disease after Crohn remains controversial. While Crohn, in his memoir, describes his original investigation of the disease, Ginzburg provided strong evidence of how he and Oppenheimer were the first to study the disease.Signs and symptoms
Gastrointestinal
Many people with Crohn's disease have symptoms for years before the diagnosis. The usual onset is in the teens and twenties, but can occur at any age. People with Crohn's disease experience chronic recurring periods of flare-ups and remission.Perianal
discomfort may also be prominent in Crohn's disease. Itchiness or pain around the anus may be suggestive of inflammation of the anus, or perianal complications such as anal fissures, fistulae, or abscesses around the anal area. Perianal skin tags are also common in Crohn's disease, and may appear with or without the presence of colorectal polyps.Intestines
The intestines, especially the colon and terminal ileum, are the areas of the body affected most commonly. Abdominal pain is a common initial symptom of Crohn's disease, especially in the lower right abdomen. Flatulence, bloating, and abdominal distension are additional symptoms and may also add to the intestinal discomfort. Pain is often accompanied by non-bloody diarrhea, however in some cases the diarrhea can be bloody. Inflammation in different areas of the intestinal tract can affect the quality of the feces. Ileitis typically results in large-volume, watery feces, while colitis may result in a smaller volume of feces of greater frequency. Fecal consistency may range from solid to watery. In severe cases, an individual may have more than 20 bowel movements per day, and may need to awaken at night to defecate. Visible bleeding in the feces is less common in Crohn's disease than in ulcerative colitis, but is not unusual. Bloody bowel movements are usually intermittent, and may be bright red, dark maroon, or even black in color. The color of bloody stool depends on the location of the bleed. In severe Crohn's colitis, bleeding may be copious.Stomach and esophagus
The stomach is rarely the sole or predominant site of Crohn's disease. To date, there are only a few documented case reports of adults with isolated gastric Crohn's disease and no reports in the pediatric population. Isolated stomach involvement is very unusual presentation accounting for less than 0.07% of all gastrointestinal Crohn's disease. However, the esophagus and stomach are increasingly understood to be affected in people with intestinal Crohn's disease. Recent studies suggest upper GI involvement occurs in 13-16% of cases, typically presenting after distal symptoms. Upper gastrointestinal symptoms may include difficulty swallowing, painful swallowing, upper abdominal pain, and vomiting.Oropharynx (mouth)
The mouth may be affected by recurrent canker sores. Recurrent aphthous ulcers are common; however, it is not clear whether this is due to Crohn's disease or simply that they are common in the general population. Other findings may include diffuse or nodular swelling of the mouth, a cobblestone appearance inside the mouth, granulomatous ulcers, or pyostomatitis vegetans. Medications that are commonly prescribed to treat Crohn's disease, such as anti-inflammatory and sulfa-containing drugs, may cause lichenoid drug reactions in the mouth. Fungal infection such as candidiasis is also common due to the immunosuppression required in the treatment of the disease. Signs of anemia such as pallor and angular cheilitis or glossitis are also common due to nutritional malabsorption.People with Crohn's disease are also susceptible to angular stomatitis, an inflammation of the corners of the mouth, and pyostomatitis vegetans.
Systemic
Like many other chronic, inflammatory diseases, Crohn's disease can cause a variety of systemic symptoms. Among children, growth failure is common. Many children are first diagnosed with Crohn's disease based on inability to maintain growth. As it may manifest at the time of the growth spurt in puberty, as many as 30% of children with Crohn's disease may have retardation of growth. Fever may also be present, though fevers greater than 38.5 °C are uncommon unless there is a complication such as an abscess. Among older individuals, Crohn's disease may manifest as weight loss, usually related to decreased food intake, since individuals with intestinal symptoms from Crohn's disease often feel better when they do not eat and might lose their appetite. People with extensive small intestine disease may also have malabsorption of carbohydrates or lipids, which can further exacerbate weight loss.Extraintestinal
Crohn's disease can affect many organ systems beyond the gastrointestinal tract.Visual
Inflammation of the interior portion of the eye, known as uveitis, can cause blurred vision and eye pain, especially when exposed to light. Uveitis can lead to loss of vision if untreated.Inflammation may also involve the white part of the eye or the overlying connective tissue, which causes conditions called scleritis and episcleritis, respectively.
Other very rare ophthalmological manifestations include: conjunctivitis, glaucoma, and retinal vascular disease.
The pathophysiology of ocular inflammation in people with Crohn's disease is complex and remains uncertain. The association between inflammatory conditions of the eye and Crohn's disease is due to many people with Crohn's disease having genetic markers such as HLA-B07, HLA-B27 and HLA-DRB1*0103. Additionally, cytokines IL-6, IL-10, and IL-17 which are produced in the bowel enter the circulatory system and travel to the eyes to trigger inflammation.
Gallbladder and liver
Crohn's disease that affects the ileum may result in an increased risk of gallstones. This is due to a decrease in bile acid resorption in the ileum, resulting in bile excretion in the stool. As a result, the cholesterol/bile ratio increases in the gallbladder, resulting in an increased risk for gallstones. Although the association is greater in the context of ulcerative colitis, Crohn's disease may also be associated with primary sclerosing cholangitis, a type of inflammation of the bile ducts. Specifically, 0.96% of people with Crohn's disease also have primary sclerosing cholangitis.Liver involvement of Crohn's disease can include cirrhosis and steatosis. Nonalcoholic fatty liver disease are relatively common and can slowly progress to end-stage liver disease. NAFLD sensitizes the liver to injury and increases the risk of developing acute or chronic liver failure following another liver injury.
Other rare hepatobiliary manifestations of Crohn's disease include: cholangiocarcinoma, granulomatous hepatitis, cholelithiasis, autoimmune hepatitis, hepatic abscess, and pericholangitis.