[Collagenous colitis: macroscopically invisible, but with various treatment options].

Two female patients, aged 54 and 67 years, respectively, had suffered from watery diarrhoea for several weeks or months without cramps or blood in the stools. The findings upon physical examination, blood and faecal examination and endoscopy were normal, and subsequent histological examination of intestinal biopsies revealed collagenous colitis. After treatment with a high-fibre diet, sulphasalazine and either prednisone or budesonide, the symptoms subsided. Collagenous colitis is a chronic watery diarrhoea disorder with unknown aetiology and pathogenesis. It is characterised by macroscopically normal mucosa, while histopathologically an abnormal thickening of the subepithelial collagenous layer and an increase in the number of intra-epithelial lymphocytes is found. There are various treatment options such as dietary fibre, mesalazine or bismuthsubsalicylate. Recently budesonide has been found to have a favourable effect both clinically and histologically. Complications of the disease are rare.