LAUSR

An 84-year-old woman was admitted to the gastroenterology department at our hospital with a 2-month history of frequent watery diarrhea. She was taking lansoprazole and aspirin. She was found to have bilateral pitting edema on her lower legs and hypoalbuminemia, and here serum albumin level was 1.9 g/dL. Additional tests revealed no proteinuria, liver dysfunction, or thyroid dysfunction. A protein leakage scintigraphy showed protein leakage from the colon (Fig. 1a). A colonoscopy identified eroded and coarse erythematous mucosa with edema, decreased vascular permeability, and the presence of pseudomembranes (Fig. 1b) with longitudinal scars (Fig. 1c). Histopathology of the colon biopsy revealed subepithelial collagen bands and lamina propria inflammation (Figs. 1d,e). Based on these findings, the patient was subsequently diagnosed with collagenous colitis (CC). We suspected that lansoprazole may have been the cause, and therefore, lansoprazole was discontinued, following which the frequent episodes of diarrhea ceased. Further examination showed that the previously observed bilateral pitting edema on her lower legs had resolved, and her serum albumin levels had increased to normal levels. A subsequent colonoscopy examination revealed that the previously identified colonic abnormalities had also resolved. Collagenous colitis (CC) is a relatively rare disease that can cause persistent non-infectious diarrhea and is characterized as a chronic inflammatory bowel disease. Importantly, CC has been associated with the use of several drugs, including proton-pump inhibitors (PPIs) and non-steroidal anti-inflammatory drugs (NSAIDs). The endoscopic findings of CC include pseudomembranes, vascular changes, and erythematous, irregular mucosa with observable defects. A majority of PPI-associated cases resolve following drug discontinuation. However, cases that do not improve after drug discontinuation and those that are not drug-related require further treatment. Budesonide is the standard treatment for such cases and is effective in the induction and maintenance of remission.