C4A and cryoglobulinemia: Clinical predictors of lymphoma include persistent salivary gland enlargement, splenomegaly, lymphadenopathy, palpable purpura, peripheral neuropathy, and cytopenias, while laboratory predictors include hypocomplementemia (particularly low C4), cryoglobulinemia, monoclonal gammopathy, and elevated beta-2-microglobulin [5,6].