Is Microscopic Colitis Really Microscopic?

which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. Microscopic colitis (MC) is characterized by chronic watery diarrhea. MC comprises two entities: collagenous colitis (CC) and lymphocytic colitis (LC), which are separated by typical histopathological characteristics. The colonic mucosa appears endoscopically normal in general so it can be diagnosed only by colonic mucosal biopsies. But, macroscopic subtle nonspecific abnormalities in the colon such as erythema, edema, or abnormal vessel pattern were seen in 60 patients of the 199 patients with LC (30%) and in 42 patients of the 105 patients with CC (29%). 1,2 But these findings have been accepted not so meaningful features in the diagnosis of MC. Exceptionally colonic mucosal tears (" cat-scratch colon ") are occasionally seen during colonoscopy in CC, and might indicate an increased risk of colonic perforation during the procedure. 3 In this issue of Gut and Liver, Park et al. 4 report their retrospective analysis comparing the endoscopic, clinical, and his-topathologic features of LC with and without mucosal lesions (MLs). The authors showed MLs were observed in seven of the 14 LC cases. Six of the MLs exhibited hypervascularity, three exhibited exudative bleeding and one exhibited edema. The patients with MLs had more severe diarrhea and were taking aspirin or proton pump inhibitors (PPIs). More intraepithelial lymphocytes were observed during histologic examination in the patients with MLs compared to the patients without MLs, although this difference was not significant. The numbers of mononuclear cells and neutrophils in the lamina propria were independent of the presence or absence of MLs. Authors focused on hypervasculaity and exudative bleeding in this report. Depending on colonoscopic examples provided , these findings are not only nonspecific, but also can be observed in patients without MC. On this report, patients with MLs showed 10 years older than patients without MLs, and they had been taking aspirin and PPI at the time of diagnosis. These medications also affect bleeding tendency. Because gross ulcer-ations can be seen rarely in patients with MC who are taking nonsteroidal anti-inflammatory drugs (NSAIDs). 5 So, we could not make any conclusion from these mucosal findings yet. By histological review, this study show more intraepithelial lymphocytes were observed in the patients with MLs compared to the patients without MLs, although this difference was not significant. As we know, MC is not evenly involved in the whole colon. …