[Nuclear size and character of the nucleolar organizer in benign and malignant follicular tumors of the thyroid gland].

Histologic sections of 11 benign and 11 malignant follicular tumours of the thyroid were compared from the point of view of subsequent practising cytologic diagnosis. Following features were analysed in 100 randomly chosen thyreocytic nuclei: maximal nuclear diameter, nucleolar organizer rates (AgNOR) inside and outside the nucleoli, total AgNOR according to a modified Crocker s et al. method, total nucleolar rate and maximal nucleolar diameter, proportion of maximal nucleolar diameter and maximal nuclear diameter, AgNOR in vicinal nontumorous thyreocytes. All of them except total AgNOR did not show any significant differences according to modified t-test. But the increase of total AgNOR in follicular carcinomas lost its significance in Duncan's test of variance analysis because of a high maximal nucleolar diameter regarding big figures in 4 carcinomas (2 of them oxyphilic celled). In most tumours AgNOR inside nucleoli could not be reliably distinguished and quantified even after shortening of silver impregnation. Mean maximal nuclear diameter bigger than 7 nm, indicating malignant follicular lesion according to literature, could not be verified in 8 tumours- it was smaller in 5 carcinomas and bigger in 3 benign tumours. Proportion of maximal nucleolar diameter and maximal nuclear diameter was stable in benign and malignant tumours as well as the AgNOR in peritumorous thyreocytes. All the analysed nuclear features are lacking in sufficient prediction value for distinction of benign and malignant follicular tumours of the thyroid.