Background. To explore the flow cytometric diagnosis of malignant lymphoma, we examined the deoxyribonucleic acid (DNA) ploidy, proliferative activities, and immunophenotype of surgical biopsy-and fine-needle aspiration (FNA)-derived materials. Our goal was to determine the possibility of making a diagnosis of malignant lymphoma by flow cytometric analysis of FNA-derived materials.
Methods. The DNA ploidy and proliferative indices including the percentage of S-phase fraction (SPF), G2 + M fraction (G2M), and Ki-67-positive fraction (Ki-67) were analyzed on the fresh materials from 84 consecutive patients with suspected malignant lymphoma. Flow cytometric analysis of surface antigens was simultaneously performed. Fourteen of the patients underwent FNA and subsequent surgical biopsy of the same lymph nodes for flow cytometric analysis.
Results. The proliferative indices of intermediate-grade non-Hodgkin's lymphomas (NHL) (n = 28) and high-grade NHL (n = 23) were significantly higher than those of the reactive hyperplasia (n = 25). The total for SPF + G2M of 6% was a satisfactory threshold for differentiating these NHL from reactive hyperplasia (sensitivity of 84%, specificity of 88%, and accuracy of 86%).
However, low-grade NHL (n = 3) and Hodgkin's lymphoma (HL, n = 5) could not be discriminated by employing this parameter. DNA aneuploidy was seen in 13 of the 28 intermediate-grade NHL and 8 of the 23 high-grade NHL, whereas it was not seen in 25 reactive hyperplasia, 3 low-grade NHL, and 5 HL. The percentage of CD19-positive cells in B-cell NHL or CD3-positive cells in T-cell NHL was significantly higher compared with those for reactive hyperplasia. The percentage of CD16 + CD56positive cells in natural killer (NK) cell NHL was extremely high, with a mean of 91.8%. Flow cytometric results for FNA-derived materials showed excellent correlation with those for surgical biopsy-derived specimens.
Conclusions. Analyses of DNA ploidy, proliferative activities, and immunophenotype by flow cytometry (FCM) are useful for diagnosing intermediate-and high-grade NHL. Fine-needle aspiration is a less invasive approach than surgical biopsy, and, when combined with FCM, it may have a place in the diagnosis of NHL.