Fine-needle aspiration evaluation of lymphoproliferative lesions in human immunodeficiency virus-positive patients. A multiparameter approach. Forty-six fine-needle aspirates of lymphoproliferative lesions from 31 human immunodeficiency virus (HIV)-positive patients were reviewed using cytomorphologic, immunocytochemical, flow cytometric (FCM), cytogenetic, and molecular studies. There were 29 lymphomas (15 small non-cleaved cell [SNCL], 11 large cell [LCL], one small lymphocytic, and two Hodgkin's), 14 reactive hyperplasias, and three "atypical lymphoid proliferations." The reactive hyperplasias were characteristically polymorphic and polyclonal lymphoid populations; six of seven were diploid on FCM, the seventh was hypodiploid. Higher proliferative indices (mean, 11.6%) and higher RNA indices (mean, 1.2) characterized this subgroup compared with published reactive lymphoid hyperplasias from patients without HIV positivity. Aspirates of SNCL showed monotonous populations of intermediate-sized cells except in one patient where a giant cell syncytial variant occurred. Nine of 13 SNCL aspirates showed light chain restriction. JH rearrangement revealed B-cell lineage in one aspirate in which immunocytochemical study was negative for Kappa, lambda, B1, and Leu-4. Nine of 12 SNCL were diploid; the mean proliferative index was 25.6% and the mean RNA index 2.3. Chromosomal translocations involving the c-myc locus were demonstrated in five of seven SNCL aspirates karyotyped. Five of eight LCL showed light chain restriction the remaining three showed null cell phenotype. Large cell lymphomas were diploid on tetraploid with the mean proliferative index of 22.0% and mean RNA index of 2.2. One of two LCL aspirates karyotyped demonstrated c-myc translocation. Despite the multiparameter approach, a definitive diagnosis could not be reached in three aspirates. 