Eric J. Zhao, Mollie N. Carruthers, Charles H. Li, Andre Mattman, Luke Y. C. Chen. Conditions associated with polyclonal hypergammaglobulinemia in the IgG4-related disease era: a retrospective study from a hematology tertiary care center. Haematologica 2020;105(3):e121-e123; https://doi.org/10.3324/haematol.2019.219725.