[Flow cytometry: application for the diagnosis and the follow-up of hematological malignancies].

Diagnosis of haematological malignancies is based on multiparametric analysis such as morphology, phenotype and genotype studies. Some entities are only defined by one of these approach. Flow-cytometry (FCM) is useful to determined the normal counterpart of the tumoral process and its differentiation status within the involved lineage. Furthermore, FCM is able to detect clonality in B or T proliferations and criteria for malignancies such as abnormal phenotype. Finally it also specifies prognosis criterias. Among the different haematological malignancies, acute lymphoblastic leukaemia (ALL) can be diagnosed using FCM, whereas acute myeloblastic leukaemia diagnosis is only confirmed by this methodology, which could moreover determine prognosis factors. A scoring system (EGIL) determine the normal counterpart of tumoral cells using a panel of different markers. Immunophenotyping is also useful in chronic lymphoproliferative disorders, such as chronic lymphocytic leukaemia (CLL) by using a similar scoring system (so-called Matutes scoring). Since FCM is able to detect simultaneously numerous cell markers it could be more accurate than immunohistochemistry for the diagnosis of follicular lymphoma, mantle cell lymphoma or hairy cell leukaemia. Finally, during treatment follow-up, minimal residual disease characterised by the detection of rare specific events, may be examined using FCM, in some situations.