CHROMOSOMAL AND DNA-PLOIDY CHARACTERIZATION OF SALIVARY-GLAND NEOPLASMS BY COMBINED FISH AND FLOW-CYTOMETRY

Concurrent DNA ploidy by flow cytometry and interphase FISH analysis o f chromosomes 6 through 12, 17, 18, X, and Y were prospectively perfor med on 22 salivary gland neoplasms (four benign and 18 malignant) to i nvestigate the diagnostic and biological implications of their alterat ions in these neoplasms. Our results show that benign neoplasms lack D NA aneuploidy and numerical chromosomal abnormalities. Low-grade malig nant neoplasms, except for two lesions, manifested small chromosomal g ains and losses and were generally DNA diploid or near-diploid aneuplo id, whereas all high-grade tumors showed marked polysomy and were DNA aneuploid. Marked intratumoral and intertumoral chromosomal heterogene ity also were noted in and between individual tumors. Although polysom y was the main finding in DNA aneuploid lesions, monosomy was more not ed in DNA diploid neoplasms and was restricted to chromosomes 8, 11, a nd 17. Significant correlation between the DNA index, chromosomal aneu somy, histological grade, and tumor stage was noted. Our study indicat es that (1) benign salivary gland neoplasms lack gross DNA content and numerical chromosomal abnormalities, (2) clonal chromosomal alteratio ns are manifested in most DNA diploid and all DNA aneuploid malignant tumors, (3) chromosomal gain is the most common alteration; chromosoma l loss is less frequent and restricted to certain chromosomes, and (4) DNA aneuploidy and chromosomal aneusomy characterize tumors with aggr essive features. (C) 1997 by W.B. Saunders Company.