When evaluating patients with different types of CTD (Figures 1B–D), serum MUC5AC was higher in the pSS-ILD, SSc-ILD, and PM/DM-ILD subgroups than in the respective non-ILD group (p=0.002, p<0.001, and p=0.003, respectively). Here, MUC5AC is linked to peeling skin syndrome.