The cytological and clinical value of the thyroid "follicular lesion".

Background: The main limitation of fine-needle aspiration (FNA) is its limited distinction between neoplastic and benign lesions. We summarize our experience with thyroid nodules that were defined as follicular lesions by comparing the clinical and cytological features of the thyroid follicular lesions that were examined histologically to define the most reliable criteria of malignancy.

Methods: The medical records of all patients who underwent thyroid aspiration at Rabin Medical Center from 1999 to 2000 were reviewed for a diagnosis of follicular lesion that warranted surgery (N = 58). The cytology and pathology reports of the patients who met these criteria were reviewed and compared with the original reports.

Results: The incidence of malignancy in follicular lesions of the thyroid is about 26%. There was a significant correlation between a histologic diagnosis of carcinoma and the cytologic findings of nuclear grooves (P =.041), solid arrangement (P =.019), hypercellularity (P =.01), and hypercellularity to colloid amount ratio (P =.016). Nodular size was predictive of malignancy. No correlation was found between patient age or gender and tendency toward malignancy.

Conclusions: The combination of cytological characteristics and the size of the nodule aspirate are predictive values of malignancy. We believe that every follicular lesion should be excised to obtain a definitive histological diagnosis based on capsular or vascular invasion.