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Biopsies revealed a thickened subepithelial collagen table, increase in the intraepithelial lymphocytes and inflammation of the lamina propria, characteristic of collagenous colitis (CC). CC is associated with normal or almost normal colonoscopy and clinically follows a benign course. The concurrent presence of mucosal lacerations and/or fractures in the thin-walled right colon with hypertrophic (celoid type) mucosal scars in the left colon is considered highly suggestive of CC. ^[1] Moreover, a mosaic or "honeycomb" mucosal pattern with disarranged innominate mucosal grooves, is indicative of CC. It has been shown that chromoendoscopy with indigo carmine accentuates those changes thereby aiding in endoscopic diagnosis of CC. ^[2],[3]

Index of Haemoglobin (IHb) features an algorithm that increases the redness of mucosa, based on the received R (red) and G (green) signals. Therefore, mucosal areas of increased blood supply are accentuated in red. It is incorporated in the EVIS LUCERA videoscope system (Olympus^® Tokyo, Japan) and is applicable for image analysis of endoscopic color and enhancement of the mucosal vascular flow change. ^[4] Enhancement of mucosal pattern either with indigo carmine chromoendoscopy or IHb application, especially when other colonoscopic findings (mucosal fractures, scars or lacerations) are strongly suggestive of CC, should be considered as a further useful step towards an "on-the-spot" diagnosis and should prompt initiation of therapy without delay. In the first case, budesonide was commenced during a hospital re-admission, as beta-blockers and lansoprazole discontinuation had no effect.

By that time, biopsies had confirmed thickening of the sub-epithelial collagen band and an extensive denudation of the surface epithelium with focal increase of the intraepithelial lymphocytes. The second patient received budesonide immediately post-colonoscopy with remarkable effect.

In conclusion, we recommend that in cases with pathognomonic colonoscopic findings, therapy should be started immediately post-endoscopy, thus avoiding unnecessary delays in patient management.