CD79A and common variable immunodeficiency: If the study of this patient had shown low serum levels of IgG and IgM and/or IgA, we would have concluded that, of the whole hepatobiliary process, undifferentiated arthritis, splenomegaly, and the lymphoproliferative processes of the skin, muscle, fascia, lymph nodes, and mediastinum were most probably due to CVID.