Comparative analysis of DNA ploidy and proliferative index in fine needle aspirates of non-Hodgkin's lymphomas by image analysis and flow cytometry

To determine the application of image analysis (IA) to fine needle aspiration (FNA) of non-Hodgkin's lymphomas, 78 cases, categorized according to the Working Formulation, were analyzed and compared with those analyzed by flow cytometry (FCM). Aspirated material was immediately fixed in either IA fixative (31 cases) or acetone, stored at -70° C (47 cases) for periods up to 48 months and postfixed in IA fixative. IA assessed DNA index (DI), ploidy balance, degree of hyperdiploidy and proliferation index (PI). DNA index, % S + G₂M and RNA index were obtained by acridine orange FCM. There were no significant differences in measured variables between fresh and stored cases. Statistically significant differences between low, intermediate and high grade lymphomas were present in all evaluated variables except DNA ploidy (DI) (P = .074) measured by IA. DI, however, showed a very high correlation with the DI obtained by FCM (r = .94). PIs, although generally lower, also had a high correlation with S + G₂M (r = .85). We conclude that results obtained by IA were comparable to results by FCM and that frozen material can be used to retrospectively evaluate ploidy and proliferation. IA is especially suitable for the evaluation of low-volume specimens obtained by FNA.