Burrill Bernard Crohn at Mount Sinai Hospital in 1907. He was promoted to head of gastroenterology in 1920, the same year he joined the staff of Columbia University. Working with colleagues at Mount Sinai Hospital, Crohn identified fourteen patients whose symptoms and intestinal abnormalities discovered at surgery, while consistent with each other, did not fit any previously identified disease. Crohn, along with Leon Ginzburg and Gordon Oppenheimer, prepared the classic paper describing this new condition. This paper was read at a professional meeting in May 1932 and published in the "Journal of the American Medical Association" in October 1932. The title of the
Burrill Bernard Crohn that it was caused by the same pathogen, a bacterium called "Mycobacterium paratuberculosis" (MAP), responsible for the similar condition that afflicts cattle called Johne's disease. However, he was unable to isolate the pathogen—most likely because "M. paratuberculosis" sheds its cellular wall in humans and takes the form of a spheroplast, making it virtually undetectable under an optical microscope. This theory has resurfaced in recent years, and has been lent more credence with the arrival of more sophisticated methods of identifying MAP bacteria. Crohn noted that it can be difficult for physicians to correctly differentiate neuroses from diseases of the organs.