Abstract
Objective : We attempted to improve aspiration cytology accuracy and reliability in detecting thyroid follicular neoplasm by comparing the cytological features of follicular carcinoma and adenoma.
Study Design : Cytological readings were retrospectively evaluated for histology in 57 cases of follicular carcinoma and 755 of follicular adenoma.
Results : Sensitivity was 35%, specificity 97%, and positive and negative predictive value 50% and 95% in the aspiration cytology detection of thyroid follicular neoplasms. Follicular adenoma frequently demonstrated a thin colloidal background (54%), sheet patterns (54%), and microfollicular patterns (18%). Follicular carcinoma demonstrated increased cellularity (21%), microfollicular patterns (23%), nuclear atypia (25%), and coarse granular or dense chromatin (33%). Follicular carcinomas reported as malignant in cytology showed more nuclear atypia and coarse granular chromatin than those reported as benign.
Conclusion : Many follicular carcinomas can be diagnosed as malignant in aspiration cytology based on neoplastic cell pattern, coarse granular chromatin, and increased chromatin, and should be correctly evaluated and reported as malignant.
