A practical guide to assess the Nancy histological index for UC

Recently, we published the first validated index to assess histological disease activity in UC.1 We believe that some clarifications have to be made regarding the assessment of this index in both clinical practice and clinical trials. Three histological criteria have to be assessed. The first criterion is the presence of mucosal ulceration defined by the loss of colonic crypts replaced with ‘immature’ granulation tissue (defined as disorganised blood vessels with extravasated neutrophils) or the presence of fibrinopurulent exudate. The presence of only epithelial stripping should not be considered as ulceration. ‘Ulceration’ (grade 4 of the Nancy index corresponding to severely active disease) is simply defined by the presence or absence of this criterion on biopsy specimen (figure 1A, B). Figure 1 (A) Ulceration of colonic mucosa with inflamed granulation …