MULTIVARIATE KARYOMETRIC APPROACH IN DIFFERENTIAL-DIAGNOSIS OF FOLLICULAR THYROID NEOPLASMS - A STUDY OF 31 CASES

A retrospective analysis of 19 follicular adenomas, 12 minimally invas ive follicular carcinomas and 3 widely invasive follicular carcinomas of the thyroid was performed on 5-mu m-thick Feulgen-stained paraffin sections by means of a semiautomatic system for picture analysis. The major aim was to assess the potential of multiparameter karyometry for separation of the first two tumour types. Sixteen planimetric and den sitometric features were defined in each case on 200-300 randomly sele cted nuclei and processed by a number of uni- and multivariate statist ical methods. Despite predominantly significant ANOVA results a substa ntial overlap between tumour groups limited the practical usefulness o f any karyometric feature alone. Factor and cluster analyses indicated independence of planimetric and densitometric parameters from each ot her, which was of crucial importance in finding an optimal subset of v ariables for discriminant analysis. The classification rule derived fr om the latter procedure was checked by the ''jack-knife'' method, by c lassification of 3 widely invasive cancers and by hierarchical tumour clustering. Sensitivity and specificity of the model for detection of malignancy were 100% and 94.7%, respectively. A multivariate karyometr ic approach, when applied correctly, can be a useful tool for differen tiation between follicular adenomas and minimally invasive follicular carcinomas of the thyroid.