It remained to the group of clinician-investigators at The Mount Sinai Hospital, New York, Burrill B. Crohn, Gordon Oppenheimer and Leon Ginzburg, to publish the classic paper, entitled “Regional ileitis: a pathological and clinical entity” in 1932
Crohn disease, as this entity was later coined, is a chronic inflammatory disease of unknown etiology, which potentially involves the gastrointestinal tract from the mouth to the perianal area.
CD may affect people in early childhood until late adulthood, but younger individuals, including teenagers and young adults, are more often affected. Afflicted patients have a significant decrease in the quality of life because of the marked morbidity. This disease also has a significant economic impact since most patients are affected in their productive years. The incidence seems to be increasing worldwide, even in low-incidence regions, probably because of better diagnosis. Environmental factors as well as changes in life style may also have an impact. The highest incidence rate has been reported in Canada (248/100,000 inhabitants), while in Asia the rate is less than 6.3/100,000 inhabitants.
Although the etiology is still not understood, several theories have been proposed over the years.
Mycobacterium avium subspecies paratuberculosis has been implicated in the pathogenesis of CD, reinforced by the great similarity between CD and cattle’s Johne disease. This association has been supported by many studies
Clinical manifestations vary greatly in the manner gastrointestinal and extra-intestinal involvement is expressed. The majority of patients have small bowel involvement, predominantly in the ileum, while as many as 20% have the disease confined to the colon. Quite frequently, symptoms are present two to three years before the diagnosis is established. Patients typically have diarrhea, often bloody, abdominal pain, fatigue, weight loss with emaciation, and fever.
Extraintestinal manifestations that can be seen are arthritis, skin and eye involvement, primary sclerosing cholangitis leading to secondary biliary cirrhosis, secondary amyloidosis, hypercoagulability, renal stones, osteoporosis, vitamin B12 deficiency and pulmonary involvement.
Currently, diagnosis of CD usually requires imaging studies, endoscopy, serologic markers and evaluation of inflammatory-marker protein tests.
Colonoscopy with terminal ileum examination is used to establish the diagnosis of ileocolonic CD. Focal ulcerations intermingled with normal-appearing (“skip”) areas is typical. Polypoid mucosal changes give a distinctive cobblestone appearance, characteristic of CD, although, in the large intestine, longitudal ulcers, resembling furrows made by a garden rake, are often seen. Carcinoma can develop after many years of active disease, but is exceedingly rare with modern methods of following patients as well as with effective therapies.
Geller SA. Pathology of inflammatory bowel diseases. In: Targan S, Shanahan F, editors. Inflammatory bowel disease. Baltimore: Williams and Wilkins; 1994. chap. 23; p. 336-351.