The mean IgG3 (mg/dl) level was 80.5 ± 79.8 in the IgG4-SC group, 74.2 ± 47.8 in the PSC group, and 42.5 ± 25.8 in the CCA group (p = 0.053). Here, IGHG3 is linked to pancreatic serous cystadenoma.