Differences were identified for CK20 and nuclear β-catenin, which were significantly more often expressed in FCCTX than in Lynch syndrome (p < 0.001), whereas MUC2, MUC5AC and MUC6 were overexpressed in Lynch syndrome tumors compared with FCCTX tumors (p = 0.001, < 0.01, and < 0.001, respectively). This evidence concerns the gene MUC6 and Lynch syndrome.