Polyclonal B-cell lymphocytosis: Report of three cases.

BACKGROUND: Persistent polyclonal B-cell lymphocytosis (PPBL) is a rare benign condition characterized by a polyclonal B-cell lymphocytosis with binucleated lymphocytes. We hereby report three cases of PPBL. METHODS: Flow cytometry immunophenotyping was performed in peripheral blood samples from three patients with clinical suspicion of lymphoproliferative disease. RESULTS: Case 1 was a female middle-aged smoker; Case 2 was an elderly male; and Case 3 was a non-smoker female. Flow cytometry evaluation of all cases revealed an expansion of mature B-cells, with a normal Kappa/Lambda light chain ratio; B-cell lymphocytes of Cases 2 and 3 had CD5 coexpression; Case 3 also had monocytosis. CONCLUSIONS: Diagnose of PPBL is important in order to avoid unnecessary diagnostic procedures and therapy. © 2018 International Clinical Cytometry Society.