General approach to the workup of lymphocytosis. BM, bone marrow; CMV, cytomegalovirus; CTD, connective tissue disease; EBV, Epstein-Barr virus; FL, follicular lymphoma; HCL, hairy cell leukemia; HTLV, human T-lymphotropic virus; LGL, large-granular leukemia; LN, lymph nodes; LPL, lymphoplasmacytic lymphoma; MCL, mantle cell lymphoma; MF, mycosis fungoides; T-PLP, T prolymphocytic leukemia; SMZ, splenic marginal zone lymphoma; T-leu, T-cell leukemia; VZV, varicella zoster virus.