ESCCA/ISCCA protocol for the analysis of cerebrospinal fluid by multiparametric flow-cytometry in hematological malignancies

Central nervous system (CNS) involvement is a serious but often underdiagnosed complication of hematological malignancies. Currently, the gold standard to detect CNS involvement is conventional cytology (CC) whose sensitivity though is lower than 50%. Multiparametric flow cytometry (MFC) demonstrated a superior sensitivity over CC, particularly when low levels of CNS infiltrating cells are present. Although prospective studies are few, a positive finding by MFC appears to anticipate an adverse outcome even if CC shows no infiltration. However, the use of MFC to diagnose CNS involvement presents some pitfalls, due to the typical hypocellularity of cerebrospinal fluids (CSF), and low cell vitality. Furthermore, the threshold to be used for defining the MFC positivity is not universally defined. In this paper, a working group of the European Society for Clinical Cell Analysis-ESCCA-and the Italian Society for Clinical Cell Analysis-ISCCA-will discuss the critical aspects of CSF processing, highlighting difficulties in storage and processing of samples, interpretation and reporting of data.