Thyroid neoplasms. Can we do any better with quantitative cytology?

The differential diagnosis of thyroid neoplasms by routine cytology presents major difficulties. We therefore looked for measurable nuclear parameters that could be generated from Feulgen-stained smears obtained by fine needle aspiration biopsy (FNAB). These parameters would then be used to differentiate between benign and malignant lesions. Seventy-six patients whose cold thyroid nodule was surgically excised after FNAB and examined by a pathologist were used in this study: 56 benign, 18 malignant and 2 atypical adenomas. A set of 3,662 cells from the 33 benign cases was compared with the set of 1,712 cells from the 11 malignant nodules. Discrimination between the two populations was based on four nuclear features ranked according to their discriminating power. The first ranked was a textural parameter, followed by a densitometric and finally two other textural parameters. The rate of nuclei that could be regarded as benign was computed for each case using the ranked parameters. The average rate for the 33 benign cases was 85% (50.2 = 100%, set at the 95% confidence interval). In a prospective study of the 32 remaining patients, sensitivity and specificity were, respectively, 92% and 88%, which were higher than those obtained by conventional cytology.