Two AgNOR counts in fine‐needle aspirates of lymphoproliferative disorders compared with acridine orange flow cytometry

Studies have shown that argyrophilic nucleolar organizer region‐associated proteins (AgNORs) may correlate with DNA ploidy and/or proliferative activity in neoplastic and non‐neoplastic conditions. However, studies have estimated only the mean AgNOR counts. Here we used two AgNOR counts, one of which may correlate with DNA ploidy and the other with proliferative activity. The mean AgNOR count (mAgNOR) was defined as the mean number of AgNORs/nucleus in 100 cells and may represent DNA or RNA index. The percentage of nuclei exhibiting 5 or more AgNORs/nucleus (pAgNOR) may reflect proliferative activity. These two AgNOR counts were correlated with results from acridine orange flow cyotmetry in 50 fine‐needle aspirate (FNA) smears of nodal and extranodal sites, including three cases of reactive lymphadenopathy and 47 cases of non‐Hodgkin's lymphoma. The mean mAgNOR count in the diploid specimens was 2.03 (±0.74 SD) and 2.62 (±0.73 SD) in the aneuploid tumors (P < 0.0001). Samples with a low RNA index had mean mAgNOR of 1.80 (±0.41 SD), whereas those with high RNA had a mean mAgNOR of 2.93 (±0.86 SD) (P <0.0001). Lesions with low proliferative index, determined by flow cytometry, had a mean pAgNOR of 4%, whereas those with intermediate and high proliferative indices had a mean pAgNOR of 16% (P <0.0001). A similar but less significant correlation existed between RI and pAgNOR (P < 0.005). We conclude that the two AgNOR counting methods may reliably reflect cell kinetics and distinguish ploidy from proliferative activity, making them useful adjuncts to flow cytometry in limited cytology specimens and small biopsy samples. © 1992 Wiley‐Liss. Inc.