History of early research on Crohn's disease.

Early attempts at finding a cause.

Since Crohn's disease was first encountered, it has been theorised that the disease is caused by infection with a mycobacterium. This extract from "Crohn's Disease and the Mycobacterioses: A Review and Comparison of Two Disease Entities" describes the early history of attempts to find a cause for Crohn's disease.

"Mycobacteria and Crohn's disease: a historical perspective." "Medical historians suggest that Crohn's disease may first have been described as early as 1682 to 1771, or perhaps earlier. Reports of diseases suggestive of Crohn's disease have appeared in 1806, 1813, 1828, 1875, 1907, 1908, 1909, and 1913. Whether these cases actually were Crohn's disease will remain unknown. Mycobacteria were not discovered until 1874 when Hansen described acid-fast bacilli in leprosy patients. The organism causing tuberculosis, which would be confused with Crohn's disease for years to come, was not discovered until 1882, and intestinal tuberculosis was not recognized until several years later. Nevertheless, a disease was described in the early 1900s that was similar to intestinal tuberculosis, but acid-fast organisms could not be isolated. Dalziel, in 1913, described several patients with chronic intestinal enteritis which, although very similar to intestinal tuberculosis, was believed to be a new disorder. He drew attention to a recently described disease in cattle called pseudotuberculosis (now known as paratuberculosis) 'in which the histological characters and naked-eye appearances are as similar as may be to those we have found in man.' Dalziel goes on to state: 'In many cases the absence of acid-fast bacilli would suggest a clear distinction, but the histological characters are so similar as to justify a proposition that the disease may be the same.' Also in 1913, contrary to the views of Dalziel, Ignard wrote: 'In many cases of hyperplastic tuberculosis of the intestine, no tubercles, giant cells or bacilli are found. The lesion consists of a mixture of variable proportions of tuberculous and inflammatory elements. In certain cases, the last only exists. Nevertheless, these inflammatory tumors should be classified among the tuberculous.' The view of Ignard predominated, and these unusual intestinal diseases became known as hyperplastic tuberculosis." "By the 1920s, the belief was fading that intestinal tuberculosis occurred without acid-fast bacilli or caseous necrosis, and a disease known as 'nonspecific granulomata' emerged. In these cases, as well as in those described by Crohn et al. in later years, the authors each discussed 'the remarkable resemblance' of these cases to intestinal tuberculosis. The landmark article by Crohn, Ginzberg, and Oppenheimer recognized regional ileitis as a separate and unique disease entity and displaced the long held belief of a mycobacterial etiology. We now know that hypertrophic intestinal tuberculosis and tuberculosis without caseation or demonstrable acid-fast bacilli do exist, as does a distinct disease known as Crohn's disease. Nevertheless, over the years, the notion recurs that Crohn's disease might in fact be mycobacterial in origin."

Crohn's disease: a shifting clinical entity.

Even after Crohn et al. provided a convincing defintion of the disease, that definition proved to be insufficient. This extract, again from "Crohn's Disease and the Mycobacterioses: A Review and Comparison of Two Disease Entities", discusses the change in the recognition of Crohn's disease after 1932, and the continuing confusion between Crohn's disease and ulcerative colitis.

"What is Crohn's Disease?" "The disease that Crohn's, Ginzberg and Oppenheimer described in 1932 was a chronic low-grade inflammation of the terminal ileum. Earlier cases may have been documented, but the authors failed to receive recognition for describing a new disorder. These earlier cases were called nonspecific granulomata and were separated from those that had previously been termed hyperplastic tuberculosis of the intestine. Although Crohn's disease was first described as a segmental disease of the small intestine, in 1960 it was recognized that the same disorder affected the colon and had been confused with ulcerative colitis. In recent years, the lesions of Crohn's disease have been recognized in the mouth, larynx, esophagus, stomach, skin, muscle, synovial tissue and bone. Thus, Crohn's disease may be considered a newly recognized disease, with a defined clinical and pathologic description dating back only to the 1960s. Although the terms Crohn's disease, Crohn's colitis, Crohn's ileitis, and regional ileitis have been with us longer, there is uncertainty as to the accuracy of these diagnoses prior to 1960. To this date, Crohn's disease and ulcerative colitis continue to be confused clinically, and the term inflammatory bowel diseases (IBD) was developed to include both diseases."

Source: http://archive.crohn.ie/history.htm
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