THE ROLE OF FLOW-CYTOMETRY IN THE DIAGNOSIS OF LYMPHOMA - A CRITICAL ANALYSIS

Flow cytometry, now used routinely to aid in the classification of leu kemias, is increasingly being evaluated as a rapid technique for deter mination of surface antigens on the cells teased from lymph nodes and other masses with suspected lymphoma. The present study reviews biopsy specimens from patients examined during a two year period which were sent for flow cytometry with a diagnosis of suspected lymphoma. Sixtee n of 25 samples (64 percent) produced cell suspensions of sufficient q uantity and quality to be diagnostically helpful. Results showed that in 9/16 (56 percent) the diagnosis of lymphoma or cancer could be susp ected by flow cytometry alone, while 4/16 were consistent with the fin al tissue diagnosis of normal or reactive hyperplasia. Three samples t hat came from patients who had morphologic evidence of malignant disea se on biopsy (two Hodgkin's disease and one large cell lymphoma) had f low cytometry results that were interpreted as normal. Flow cytometry is rapid and appears to be virtually diagnostic of non-Hodgkin's lymph oma when a majority of cells are B cells with an abnormal kappa/lambda ratio (>4.0 or <0.25). Nonhematologic malignancy can be suspected if less than 75 percent of the cells show CD45 (common leukocyte antigen) . Hodgkin's disease cannot be detected by flow cytometry as it is curr ently used, and as many as 15 percent (1/6 in this study) of lymphomas may show normal results. It is extremely helpful when the biopsy samp le actually contains the cells of interest in large proportion. Loss o f architectural relationships in the course of processing specimens fo r flow cytometry is a major disadvantage when small foci of lymphoma o r tumor cells exist together with large amounts of stroma or normal ly mphocytes.