Lymphoma diagnosis: lessons learned from the comparison of histology and cytology associated with flow cytometry

For lymphoma diagnosis, the flow cytometry (FCM) and cytology associated with FCM (C-FCM) performed on fine needle aspiration (FNA) or cell suspension/imprints from fresh tissue display a good concordance (from 85 to 90%) with the diagnosis made using histological data. Herein is reported a retrospective series of discordant cases, five of them are discussed in details, and some recommendations are proposed for the interpretation of C-FCM data. Firstly, this review highlights the importance of analyzing simultaneously the cytological and FCM data. In particular, the cytological data are crucial to interpret FCM data and/or to complete Ab panels when the strategy of the laboratory is to systematically perform a first screening, which don't always allow the detection of lymphoma cells. Secondly, this report underlines that cytology and FCM analysis should be followed by a confrontation/discussion with a pathologist. Finally, C-FCM appears to be a rapid and particularly important technic to guide the choice of the following diagnosis tools (IHC and genetic).