[Adult Lymphocytosis Etiology by Flow Cytometry].

BACKGROUND:Positive and differential diagnosis of chronic lymphocytic leukemia (CLL) is based on immunophenotyping analysis. CLL is searched whenever a persistent lymphocytosis is found.AIM:To evaluate the performance of flow cytometry in etiologic diagnosis of lymphocytosis. Could it allow us to distinguish CLL from other causes of lymphocytosis?METHODS:Blood samples from 104 adult patients having a rate of lymphocytes> 5000 élé/mm3 persisting more than three months were analyzed using a large panel of monoclonal antibodies in three colors and Cell Quest software. results: Lymphoproliferative B disorder was retained in 83 cases, including 50 cases of typical CLL with Matutes score≥ 4 and 12 cases of atypical CLL with Matutes score = 3 . Diagnosis of hairy cell leukemia and follicular lymphoma were guided by the respective specific antigen expression CD103 and CD10. Large granular T lymphoma (LGL-T) was the most common etiology of lymphoid T proliferation. Unusual cases of Natural Killer (NK) and NK/T proliferations were found.CONCLUSION:The Flow cytometry is a powerful tool to establish lymphocytosis etiological diagnosis; it avoids invasive investigations in a large number of cases.