Differential diagnosis of fine needle aspiration smears of thyroid nodules. Cytologic features and AgNORs.

ABSTRACT

OBJECTIVE: To determine the value of cytomorphologic features and argyrophilic nucleolar organizer regions in fine needle aspiration smears of thyroid nodules. STUDY DESIGN: Cytomorphologic features were analyzed for frequency and predictive value in smears of 60 histologically confirmed cases of thyroid nodules, comprising 16 cases of papillary carcinoma, 19 of follicular adenoma, 5 of follicular carcinoma, 3 or medullary carcinoma and 17 of adenomatous goiter. The smears were also stained for AgNORs to compare AgNOR counts in these lesions. RESULTS: Intact follicles and abundant background colloid were useful for the diagnosis of adenomatous goiter; metaplastic cells, nuclear grooves and multinucleate giant cells predicted the diagnosis of papillary carcinoma; and acinar formations were important in the diagnosis of follicular adenoma and follicular carcinoma. AgNOR counts showed major overlaps among the various groups, although the mean counts in neoplastic lesions were slightly higher than those in adenomatous goiter CONCLUSION: AgNOR counts failed to have any significant diagnostic utility, and the fine needle aspiration cytology diagnosis of thyroid nodules must still be based on a combination of cytologic features.