[363] Impact of Eight-Color Flow Cytometry on the Diagnosis of Cerebrospinal Fluid (CSF) Involvement by Leukemia or Lymphoma.

Jennifer D Duven, Carol J Holman, Timothy Singleton, Adina M Cioc, Dan M McKeon, Stefan E Pambuccian. University of Minnesota, Minneapolis

Background: Cytologic examination (CYT) of the CSF has long been the standard diagnostic procedure for detection of leukemia and lymphoma (L&L) in the CSF. However, recent reports have shown an increase in the detection rate of CSF involvement by L&L ranging from 20% to 600% by the concomitant use of flow cytometry (FC).
The aim of this study was to determine the impact of 8-color FC, a method ideally suited for hypocellular samples such as CSF, on the diagnosis of CSF involvement by L&L.
Design: All cases that had CYT and FC performed on samples obtained from the same lumbar puncture from 1/1/08 to 8/1/10 were identified. CYT and FC diagnoses were independent, the CYT diagnosis usually preceding the FC interpretation. 8-color FC was performed on a BD FACS Canto II flow cytometer. The typical antibody panel consisted of CD5, CD10, CD19, CD20, CD45, κ, λ and either CD14, CD38, CD56 or CD58 depending on the L&L suspected, with a secondary T-cell or myeloid panel performed as needed. Age and sex of the patient, L&L type, CYT and FC interpretations were entered into a spreadsheet for analysis.
Results: We identified a total of 282 cases from 143 patients. 78M/65F, aged 4-84 (mean 51) with diagnoses of acute lymphocytic leukemia (n=23), acute myelocytic leukemia (n=28), acute bilineage leukemia (n=1) chronic lymphocytic leukemia (n=4) chronic myelocytic leukemia (n=3) hairy cell leukemia (n=1), lymphoma (n=57), and other diagnoses (n=26). Of the 19 CYT+ cases, 8 were lymphomas and 11 leukemias (AML, ALL, CLL, CML); the FC+ cases were 9 lymphomas and 23 leukemias (AML, ALL, CML).

Comparison of Flow Cytometry and Cytology Results

	FC Negative	FC Atypical	FC Suspicious	FC Positive
CYT Negative	214	2	9	13
CYT Atypical	13	1	4	1
CYT Suspicious	1	0	1	2
CYT Positive	1	0	2	16

84% of CYT+ cases were FC+; 50% of FC+ cases were also CYT+; The use of FC resulted in the diagnosis of 12 additional cases, corresponding to an increase in identification of CSF involvemnt by L&L of 168%. However, FC was negative, atypical, or suspicious in 3 of the CYT+ cases.
The sensitivity, specificity, PPV, and NPV for CYT+ as compared to FC+ were: 0.50 (0.38-0.58), 0.98 (0.96-0.99), 0.76 (0.58-0.89), and 0.94 (0.92-0.95), respectively.
Conclusions: FC aids in the identification of CSF involvement by L&L and should be used in conjunction with CYT whenever CSF involvement by L&L is suspected. Our data suggests that a management algorithm which would only perform FC when CYT findings are atypical or above would miss a significant number of cases with L&L involving the CSF.
Category: Cytopathology

Monday, February 28, 2011 9:30 AM

Poster Session I Stowell-Orbison/Surgical Pathology/Autopsy Awards Poster Session # 64, Monday Morning