Flow Cytometry Can Diagnose Classical Hodgkin Lymphoma in Lymph Nodes With High Sensitivity and Specificity

The diagnosis of classical Hodgkin lymphoma (CHL) has been made in tissue sections as attempts to identify neoplastic Hodgkin and Reed Sternberg (HRS) cells in lymph nodes by flow cytometry (FC) have been unsuccessful. However, we have recently demonstrated that HRS cells can be identified by FC, often present as T-cell-HRS-cell rosettes. In this study, we examined the usefulness of a novel 9-color (CD95-Pacific blue/CD64-fluorescein isothiocyanate/CD30-phycoerythrin [PE]/CD45-PE-Texas red/CD40-PE cyanine [Cy]5.5/CD20-PECy7/CD15-allophycocyanin [APC]/CD71-APC-AlexaFluor A700/CD5-APC-Cy7), single tube FC assay to diagnose CHL in lymph nodes. We used the FC assay to determine diagnostic sensitivity and specificity in 279 blindly identified and 141 selected (for specimen type or cytopreparation morphologic features suggesting CHL) tissues. Of the 53 morphologically defined CHL cases identified (10 in the unselected group; 43 in the selected group), the FC assay diagnostic sensitivity and specificity were 88.7% and 100%, respectively. With the current availability of 8 (or more) color clinical flow cytometers, this assay can now be applied to routinely immunophenotype and confirm a diagnosis of CHL or as an adjunct to immunohistochemical analysis.