[1579] Flow Cytometric Analysis of Fine Needle Aspirates Is Affected by Tumor Subtype

Christopher J VandenBussche, Syed Z Ali, Kathleen H Burns, Christopher D Gocke, Milena Vuica-Ross, Michael J Borowitz, Amy S Duffield. Johns Hopkins Medical Institutions, Baltimore, MD

Background: Material obtained by fine needle aspiration (FNA) is submitted for flow cytometric (FC) analysis when a hematologic malignancy is suspected. FC provides immunophenotypic data that complements morphologic findings; however, in some cases it remains difficult to perform a definitive characterization of the pathologic process.
Design: FNA specimens submitted for flow cytometric analysis from 2005 to 2010 were identified. Specimens were obtained with or without ultrasound-guidance, and were stained with Diff-Quik and Papanicolaou stains. Needle rinses were sent in Hank's solution for FC analysis.
Results: A total of 266 FNAs were examined by FC analysis. FC sampling was sufficient in 85% (226/266) of cases. A definitive diagnosis was rendered in 85% (193/226) of cases with adequate FC sampling. The probability of a definitive diagnosis varied by site and was lowest in bone (75%; 15/20) but somewhat higher in lymph node (83%; 141/170) and all other sites (88%; 67/76). The probability of a definitive diagnosis also varied by sampling method, with bronchoscopic and endoscopic FNAs having the highest success rate (100% each; 24/24 and 6/6, respectively), followed by manual (85%; 28/33) computed tomography (84%; 16/19) and ultrasound guided biopsies (82%; 149/182).
The percentage of cases that had inadequate material for FC was associated not only with the site and sampling method, but also with the tumor subtype. Hodgkin lymphoma (HL) had the highest rate of inadequate sampling (29%, 2/7), followed by follicular lymphoma (FL; 25%, 2/8), large B-cell lymphoma (LBCL; 15%, 6/40), benign nodes (12%, 4/33) and low grade B-cell lymphomas (2%; 1/45).
There was a discrepancy between the FC and morphologic diagnosis in 30 cases; in most cases (70%, 21/30) FC did not detect the presence of atypical or malignant cells that were identified on the smears and/or tissue sections. The majority (71%; 15/21) of these patients were ultimately diagnosed with a malignancy, most frequently LBCL (9) and HL (4). Nine cases had phenotypically abnormal populations on FC but normal morphology. The majority (55.6%; 5/9) of these cases was called atypical, and three patients had a follow-up biopsy; one patient had DLBCL, but the other two had benign conditions.
Conclusions: FNAs obtained from bone or from all other sites involved by HL, LBCL and FL are more likely to have a limited or inadequate FC sampling, and a core biopsy is recommended for all suspected lymphomas. Additionally, clonal populations seen on FC should be interpreted cautiously in the absence of a morphologic correlate.
Category: Hematopathology

Wednesday, March 21, 2012 9:30 AM

Poster Session V # 210, Wednesday Morning

 

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