Flow Cytometry Detects Lymphoproliferative Disorders in Fluid Specimens

Immunophenotypic analysis of hematopoietic cell populations by flow cytometry has emerged as a useful ancillary study in the diagnostic evaluation of serous effusions and cerebrospinal fluids (CSFs).

The evaluation of lymphoid proliferations in these specimens can be particularly problematic, given the frequent presence of coexisting inflammatory conditions and the manner in which these specimens are processed.

Laboratory scientists at the Hospital of the University of Pennsylvania (Philadelphia, PA, USA) searched for all serous effusions specimens such as pleural fluid, peritoneal fluid, and pericardial fluid, and CSF specimens in which flow cytometry was performed, during the time period June 2008 to July 2012. Six-color flow cytometry was performed according to the manufacturer's protocol on a FACSCanto II flow cytometer (BD Biosystems; San Jose, CA, USA). A panel using different antibodies from Becton Dickinson Immunocytometry Systems, (San Jose, CA, USA) was utilized.

Flow cytometry was performed in 184 of 6,925 total cases (2.7% of all fluids). Flow cytometry was performed in 4.8% of pleural fluids (positive findings in 38%, negative in 40%, and atypical in 18%), 1.1% of peritoneal fluids (positive in 40%, negative in 50%, and atypical in 10%), 1.9% of pericardial fluids (positive in 67%, negative in 33%), and 1.9% of CSFs (positive in 23%, negative in 55%, atypical in 3%).

The authors concluded that atypical flow cytometry findings and atypical morphologic findings in the context of negative flow cytometry results led to the definitive diagnosis of a lymphoproliferative disorder in a significant number of cases when repeat procedures and ancillary studies were performed. Flow cytometry is especially suited for cells in fluid specimens, where aggregates of cells and extracellular matrix elements that may interfere with obtaining single cells for analysis are less prominent than in solid tissue specimens. In addition, it is well known to increase the sensitivity of detecting neoplastic populations of cells over morphology alone. The study was published in the August 2014 issue of the journal Diagnostic Cytopathology.

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