[Collagenous colitis. Studies on the differentiation and incidence of the syndrome]

All colon biopsy specimens of 28 months collected in an institute of pathology, providing a region of 660,000 inhabitants were reviewed for thickening of the subepithelial layer above the normal range of 7 mu. 16 cases were found, eleven of them with mild, uncharacteristic symptoms, eight even without diarrhea. Of the five cases with collagen layers above 10 mu, three suffered from intestinal diseases (unspecific protocolitis, active ulcerative colitis and malabsorption after ileum resection); two showed chronic diarrhea as symptoms of collagenous colitis. We conclude, that a subepithelial collagen layer is without any significance. Above 10 mu, two forms can be postulated: a reactive one, following chronic intestinal diseases and the idiopathic collagenous colitis syndrome of unknown etiology and pathogenesis. The presence of 185 cases is assumed in Western Germany, five of them already published.