DNA content analysis of fine needle aspirates obtained from lymphatic tissue

DNA ploidy and S-phase fraction (SPF) of 69 lymphomas and 50 samples from benign lymphatic tissue were determined by flow cytometry from cells obtained by fine needle aspiration biopsy. An aneuploid histogram with a DNA index (DI) > 1.05 was obtained from 15 (22%) lymphomas. However, six (12%) benign lymph nodes also showed a bimodal DNA histogram, with the DI ranging from 1.06 to 1.15. The benign nature of these lymph nodes was confirmed by histology, follow-up of > 5 years or both. The median size of the SPF was 3.2%, 3.6%, 4.2%, 12.1% and 15.5% in benign lymph nodes, Hodgkin's disease and in low, intermediate and high grade non-Hodgkin's lymphomas, respectively. Only 8 (18%) of the benign tumors had an SPF > 5% as compared with 39 (62%) of the lymphomas (P < .0001). An SPF of > 12% was never obtained from benign tissue. The size of the SPF as determined from a fine needle aspirate correlates with lymphoma histology, and a bimodal DNA histogram with a small DI obtained from lymphatic tissue does not necessarily indicate the presence of lymphatic malignancy.