TP53 and ulcerative colitis: Interestingly, a diffuse-type, signet ring cell cancer (MUC2-positive and p53-negative) was covered by a MUC2-reactive “hypermucinous” non-conventional lesion (Supplementary Fig. 2) resembling those described by Andersen and coworkers [30] in the colon of ulcerative colitis patients (even though a serrated pattern was absent in our case).