The original description1 in 1932 of a granulomatous, ulcerating and stenosing inflammation of the small intestine, denominated regional or terminal ileitis, covered fourteen cases of a uniform disease, all of which had common clinical and pathologic characteristics and more or less similar topographic distributions. The almost constant involvement of the terminal ileum, the nonspecific type of granulomatous lesion, the tendency to fistula formation, both internal and external, and the frequent tendency to stenosis of the lumen of the ileum led to the inference that a purely localized and constant clinical complex and pathologic entity sufficed to cover all the variations seen to that date.
After the appearance of the paper by Harris, Bell and Brunn,2 in which an identical process was seen to involve the jejunum as well as the ileum, we were fortunate in meeting cases of this type and enlarged the original concept of ileitis to
CROHN BB, ROSENAK BD. A COMBINED FORM OF ILEITIS AND COLITIS. JAMA. 1936;106(1):1-7. doi:10.1001/jama.1936.02770010003001