Cytomorphology and flow cytometry of brain biopsy rinse fluid enables faster and multidisciplinary diagnosis of large B-cell lymphoma of the central nervous system.

Background: Central nervous system lymphomas are aggressive tumors requiring a prompt diagnosis for successful treatment. Stereotactic biopsy remains the standard procedure, but the time needed for histopathology is usually over 2 days. We evaluated the contribution of cytomorphology and flow cytometry to histopathology of the brain biopsy in particular on the rinse fluid usually removed.

Methods: Eighteen patients with suspected localized brain lymphoma underwent stereotactic brain biopsy. Brain biopsy tissue sample and/or brain biopsy rinse fluid were analyzed by cytomorphology combined with flow cytometry. Histopathology was used as a reference.

Results: Histopathology characterized ten diffuse large B-cell lymphomas and eight other diseases. Cytomorphology and flow cytometry showed lymphoma cells in nine out of the ten lymphomas. Three cytomorphology or flow cytometry negative results were reported for lymphomas in tissue samples due to low cellularity and biopsy sample conditioning. No lymphomatous cells were found by cytomorphology or flow cytometry in the eight other diseases. Rinse fluid results were consistent with histology in all cases studied (sensitivity and specificity, 100%). The median time to result was 4.5 days (range, 2-10 days) for histopathology, while 5 h (range, 3-20 h) were required for both cytomorphology and flow cytometry.

Conclusions: Brain biopsy rinse fluid alleviates problems of tissue sample distribution compared to tissue sample. Its analysis performs the diagnosis of B-cell lymphoma in a few hours and, associated with histopathology, allows a multidisciplinary diagnosis. This study shows that cytomorphology combined with flow cytometry on brain biopsy rinse fluid is a new, fast, and useful strategy. © 2016 International Clinical Cytometry Society.