Flow cytometric immunophenotyping of cerebrospinal fluid specimens
Fiona E Craig1, N Paul Ohori, Timothy S Gorrill
1Department of Pathology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA.
Insights
Flow cytometric immunophenotyping (FCI) aids in diagnosing hematologic neoplasms in cerebrospinal fluid (CSF). While valuable, especially in low-cellularity samples, FCI results require careful interpretation due to potential artifacts and indeterminate findings.
Area of Science:
- Hematology
- Immunology
- Neurology
Background:
- Flow cytometric immunophenotyping (FCI) is crucial for diagnosing hematologic neoplasms in cerebrospinal fluid (CSF).
- Evaluating CSF for malignancy is essential for patient management and treatment decisions.
Purpose of the Study:
- To assess the diagnostic utility and challenges of FCI in CSF specimens.
- To determine the positivity and indeterminate rates of FCI in CSF analysis.
Main Methods:
- Retrospective review of 230 CSF specimens analyzed by FCI.
- Specimens were categorized into primary diagnosis (n=77) and follow-up (n=153).
- Analysis included evaluation of cellularity, event counts, staining quality, and phenotypic findings.
Main Results:
- FCI was positive in 4.8% (11/230) of specimens, identifying acute myeloid leukemia, B-acute lymphoblastic leukemia, and B/T-cell lymphomas.
- Positive results were observed even in low-cellularity samples.
- FCI yielded indeterminate results in 8.3% (19/230) of cases, often due to low cellularity, artifacts, or insufficient phenotypic data.
Conclusions:
- FCI is a valuable tool for detecting hematologic neoplasms in CSF, including challenging low-cellularity specimens.
- Interpretation of FCI results requires caution due to indeterminate findings and potential artifacts.
- Further optimization may be needed to improve diagnostic accuracy in limited CSF samples.
Abstract:
Flow cytometric immunophenotyping (FCI) is recommended in the evaluation of cerebrospinal fluid (CSF) specimens for hematologic neoplasms. This study reviewed FCI of CSF specimens collected for primary diagnosis (n = 77) and follow-up for known malignancy (n = 153). FCI was positive in 11 (4.8%) of 230 specimens: acute myeloid leukemia, 6; precursor B-acute lymphoblastic leukemia, 2; B-cell lymphoma, 2; and T-cell lymphoma, 1. Positive results were obtained in low-cellularity specimens, including 2 with fewer than 100 events in the population of interest. FCI was indeterminate in 19 (8.3%) of 230 specimens, including 3 with only sparse events, 8 with possible artifact (apparent lack of staining, nonspecific or background staining, and aspirated air), and 8 with phenotypic findings considered insufficient for diagnosis. Indeterminate specimens were often limited by low cellularity and lacked normal cell populations to evaluate for appropriate staining. FCI may be of value in low-cellularity CSF specimens, although the results should be interpreted with caution.
