Karyometric marker features in fine needle aspirates of microinvasive follicular carcinoma of the thyroid.

Karyometric measurements were performed on fine needle aspirates of clearly identifiable tumor areas and adjacent normal-appearing areas in the surgical specimens from ten patients with microinvasive follicular carcinoma of the thyroid. Similar measurements were performed on aspirates from nine patients free of thyroid disease (controls). A total of 95 karyometric features were evaluated for each nucleus. As compared with the control nuclei, the normal-appearing nuclei showed a 6% increase in total nuclear optical density (OD) while the tumor nuclei showed a 14% increase. Analysis of variance indicated a significant difference between the normal-appearing nuclei and the control nuclei, with most of the difference due to the differences of tissue origin. Discriminant analysis selected nine features that produced a statistically highly significant separation of tumor nuclei from control nuclei. A similar analysis selected five features that produced a statistically highly significant discrimination of normal-appearing nuclei from control nuclei; the validity of those karyometric features as markers of malignancy in normal-appearing nuclei from tissues adjacent to microinvasive follicular carcinomas of the thyroid was demonstrated by analysis in further training and test sets of nuclei.