QUANTITATIVE CHROMATIN PATTERN DESCRIPTION IN FEULGEN-STAINED NUCLEI AS A DIAGNOSTIC-TOOL TO CHARACTERIZE THE OLIGODENDROGLIAL AND ASTROGLIAL COMPONENTS IN MIXED OLIGO-ASTROCYTOMAS

The oligoastrocytoma, as a mixed glioma, represents a nosologic dilemm a with respect to precisely defining the oligodendroglial and astrogli al phenotypes that constitute the neoplastic cell lineages of these tu mors. In this study, cell image analysis with Feulgen-stained nuclei w as used to distinguish between oligodendroglial and astrocytic phenoty pes in oligodenodrogliomas and astrocytomas and then applied to mixed oligoastrocytomas. Quantitative features with respect to chromatin pat tern (30 variables) and DNA ploidy (8 variables) were evaluated on Feu lgen-stained nuclei in a series of 71 gliomas using computer-assisted microscopy. These included 32 olinodendrogliomas (OLG group: 24 grade II and 8 grade III tumors according to the WHO classification), 32 ast rocytomas (AST group: 13 grade II and 19 grade III tumors), and 7 olig oastrocytomas (OLGAST group). Initially, image analysis with multivari ate statistical analyses (Discriminant Analysis) could identify each g lial tumor group. Highly significant statistical differences were obta ined distinguishing the morphonuclear features of oligodendrogliomas f rom those of astrocytomas, regardless of their histological grade. Whe n compared with the 7 mixed oligoastrocytomas under study, 5 exhibited DNA ploidy and chromatin pattern characteristics similar to grade II oligodendrogliomas, 1 to grade III oligodendrogliomas, and 1 to grade II astrocytomas. Using multifactorial statistical analyses (Discrimina nt Analysis combined with Principal Component Analysis), it was possib le to quantify the proportion of ''typical'' glial cell phenotypes tha t compose grade II and III oligodendrogliomas and grade LI and III ast rocytomas in each mixed glioma. Cytometric image analysis may be an im portant adjunct to routine histopathology for the reproducible identif ication of neoplasms containing a mixture of oligodendroglial and astr ocytic phenotypes.