Computation of preoperative diagnosis probability for follicular adenoma and carcinoma of the thyroid on aspiration smears.

Morphometric analysis of 23 follicular tumors (13 adenomas and 10 carcinomas) and 10 metastatic lesions from follicular thyroid carcinomas resulted in the identification of five significant parameters between the carcinoma and adenoma groups. With a classification rule using these features, the probability of a histologic diagnosis of adenoma versus carcinoma was computed for each case. Using threshold values of probabilities of 0.25 and 0.75, only 1 of the 33 cases was not correctly classified on the cytologic smear alone; the remaining 32 cases were correctly classified. These results indicate that morphometric analysis in follicular tumors of the thyroid may be of great help in individual patient care if used as a selective method by a well-trained cytopathologist.