Cytopathology and AgNOR counts in fine-needle aspiration cytology smears of thyroid lesions.

The object of the present work is to study the cytomorphological features and the value of silver colloidal staining method in distinguishing the non-neoplastic, benign, and malignant neoplasm in fine-needle aspiration cytology (FNAC) smears of thyroid nodules. One hundred forty histologically confirmed aspirated samples of thyroid lesions were studied and classified cytologically. These smears were stained for AgNOR counts. The number and location of AgNOR dots as well as clusters in nuclei were studied by two different observers independently. Lower AgNOR counts were recorded in cases of thyroiditis (1.375 +/- 0.414), whereas follicular carcinoma had a higher number of AgNOR counts (5.04 +/- 0.52). The clusters of AgNOR dots were centrally located in colloid goitre, but no cluster arrangement was observed in cases of carcinomas. Increased nuclear size, nucleoli, and chromocentres were helpful in the diagnosis of follicular carcinoma. AgNOR counting cannot be reliably used on an individual case basis to differentiate adenoma from carcinoma. Therefore, AgNOR study in thyroid lesions can be used as an additional diagnostic method with cytomorphological features to differentiate benign and malignant follicular neoplasms.