Abstract and Introduction
Abstract
Although the topic is somewhat contentious, fine-needle aspiration (FNA) is frequently used in conjunction with flow cytometry (FC) to evaluate lymphoid proliferations. Despite the fact that the FNA and FC are often analyzed independently, no previous large-scale study has independently analyzed FC of FNA specimens. FC reports of 511 FNAs were retrospectively reviewed and FC diagnoses categorized as monoclonal, atypical, normal/reactive, or insufficient cellularity (3.9%). Abnormal immunophenotype was considered a positive test result. "Gold standard" diagnoses were established by histologic examination, treatment based on FNA, or clinical features. In 92.2% (451/489), there was adequate follow-up. The diagnostic accuracy of FC was 88.4%, sensitivity was 85.8%, and specificity was 92.9%. In addition, FC accuracy for classes of non-Hodgkin lymphoma was assessed. We conclude that FC is an independently accurate ancillary test in the evaluation of FNA. However, the presence of false-negative and false-positive cases supports the common practice of correlating FC with cytomorphologic findings even if performed independently.
Introduction
The advent of modern classification systems for lymphoproliferative disorders that emphasize morphologic and immunophenotypic characteristics has ushered in a new era of increased potential for the use of fine-needle aspiration (FNA) in the evaluation of lymphoid proliferations. Ancillary studies such as flow cytometry (FC) can be combined with classic cytomorphologic features and create the potential for accurate classification of lymphoproliferative disorders. Interpretation of ancillary studies, however, depends on the performance characteristics of the given test or procedure.
Although the topic is somewhat contentious, a number of recent studies have highlighted the usefulness of FC in conjunction with FNA in the assessment of lymphoid proliferations. However, to date, no large-scale study has evaluated the independent diagnostic accuracy of FC obtained from FNA samples, with most studies limited to the diagnostic accuracy of FNA when combined with FC results. Although this integrated approach is clearly preferable, the reality is that FC is often analyzed by noncytopathologists and may be performed in a separate laboratory or institution. At times, the FC results may be reported entirely separately from the FNA morphologic results. Thus, the independent diagnostic accuracy of FC from FNA samples is of interest to cytopathologists and clinicians who must correlate FC results with cytomorphologic findings. The current study was conducted to evaluate the independent performance characteristics of FC performed on samples obtained by FNA.