Methods for the analysis of leukemic infiltration within cerebrospinal fluid in acute lymphoblastic leukemia-a systematic review.

Central nervous system (CNS) involvement in acute lymphoblastic leukemia (ALL) is associated with a poor prognosis, making its accurate detection vital for treatment planning. This systematic review critically examines the role of conventional cytomorphology (CC) and multiparameter flow cytometry (FC) in analyzing cerebrospinal fluid in acute lymphoblastic leukemia cases. While CC remains the gold standard, its sensitivity is limited, particularly in cases with low cell counts. FC offers greater sensitivity in identifying cases of 'occult' CNS disease (FC+/CC-). Pre-analytical variables, such as CSF volume, processing time, and preservation techniques, also influence the accuracy of both methods. Despite the advantages of FC, challenges remain, including the lack of standardized positivity criteria and unclear prognostic implications and management strategies for occult CNS disease (FC+ and CC-). Future research is needed to establish uniform diagnostic guidelines and to assess the clinical relevance of occult CNS disease in ALL.