QUANTITATIVE HISTOLOGIC FACTORS FOR GROUPING CHILDHOOD INFRATENTORIALNEUROGLIAL TUMORS

We employed factor analysis to quantify the degree of histologic heter ogeneity of childhood infratentorial neuroglial tumors. Our data were 26 reliably ascertained histologic features in 1068 children in the Ch ildhood Brain Tumor Consortium database. The factor analysis identifie d five uncorrelated quantitative ''factors,'' each derived from a diff erent linear combination of the 26 histologic features, that accounted for much of the histologic variation. Histologic features differed in their importance in each factor. The most important features in each factor were used for naming using simple histologic, familiar descript ive terms: Spongy, Proliferative, Ring Fibrillary and Nuclear. Each tu mor has a score on each factor. Two-thirds of tumors had high scores f or at least two factors, indicating frequent histologic heterogeneity among these tumors. Ninety-five percent of tumors were allocated to 1 of 11 nonoverlapping histologically homogeneous groups. The Jive quant itative factors complement standard qualitative taxonomies by making e xplicit the histologic heterogeneity or homogeneity of individual tumo rs and provide the pathologist with a method that takes advantage of m ore of the histology of each tumor than conventional nomenclatures. Hi stologically homogeneous groups of tumors are likely to be of value in clinical trials and biologic research. Prognostic models based on the se factors have been published.