[Collagen colitis. A new disease picture or merely a histological abnormality?]

"Collagenous colitis" has been recently defined as a new entity characterized by protracted diarrhoea, associated with subepithelial broadening of the collagen layer. A report is presented on two patients fulfilling the above criteria. Based on a critical analysis of these two cases and on prospective study of biopsies in 50 consecutive coloscopies it is concluded that a causal relationship between the enlarged collagen layer and the diarrhoea cannot be unequivocally established and hence "collagenous colitis" should not yet be considered a new entity.