Analysis of the whole BP population distribution according to BPDAI score revealed that most patients had a mild to moderate disease and that the higher the BPDAI was, the lower the number of BP patients was (Figure 1A). Such a distribution was also observed for BP patients without mucosal involvement (Figure 1B), but was significantly different in BP patients with mucosal involvement (D = 0.6154; P = 0.008). Indeed, BP patients with mucosal involvement were evenly distributed from moderate to severe disease (Figure 1C). To further understand these discrepancies, the same analysis was then performed using the separate skin activity. The relative distribution according to the erythema/urticaria BPDAI score of BP patients without mucosal involvement superposed with the one of BP patients with mucosal involvement (D = 0.1667; P = 0.991) (Figure 2A). Analysis of the distribution according to the blisters/erosions BPDAI revealed a high percentage of patients with mucosal involvement when the BPDAI values increased and a low percentage of those patients when the BPDAI values were low (D = 0.33; P = 0.433) (Figure 2B).