Between the purely functional diarrheas, on the one hand, in which we believe no anatomic changes are associated with the disturbed activities of the bowel, and the well-defined dysenteries, such as croupous and amebic colitis, on the other, in which evident and often extensive lesions are always present, there lies a large intermediate group of cases, in which it is by no means easy to be sure whether actual anatomic lesions exist or not. The main reasons for our ignorance in this matter are first: such conditions are not, of themselves, fatal in adults so that postmortem examinations are rare; and second, if the changes are only those of congestion and exudation, they may easily be impossible of demonstration after death.
To the group in question, the general term "catarrhal colitis" is applied, and it may be subdivided as follows:
Catarrhal colitis in children which may become so severe as
FLOYD R. THE LESION IN A CASE OF SEROUS COLITIS. JAMA. 1915;LXIV(23):1905-1906. doi:10.1001/jama.1915.02570490021010