CLINICAL-FEATURES ASSOCIATED WITH AN INCREASED RISK OF THYROID MALIGNANCY IN PATIENTS WITH FOLLICULAR NEOPLASIA BY FINE-NEEDLE ASPIRATION

The application of fine-needle aspiration (FNA) to the evaluation of t he thyroid nodule has greatly enhanced the ability of the clinician to appropriately select patients for thyroidectomy. However, despite ext ensive experience with thyroid FNA, the cytological distinction of ben ign from malignant follicular neoplasia remains problematic. As a resu lt, most patients with FNA findings of a follicular neoplasm are refer red for thyroidectomy. The goal of the present study was to develop cl inical criteria capable of predicting malignancy in patients with an F NA diagnosis of follicular neoplasm, Among 1121 patients undergoing th yroid FNA at two large teaching centers during the period 1990 to 1995 , 149 patients had cytological findings consistent with a follicular n eoplasm. Among 103 patients referred for thyroidectomy, 22 (21%) were found to have a malignancy in the biopsied nodule. Among patients subj ected to thyroidectomy, the risk of malignancy was significantly highe r when follicular neoplasia was present in a male (43% vs. 16% for fem ales, p = 0.007), when the nodule was greater than 4 cm to palpation ( 40% vs. 13% for nodules less than 4 cm, p = 0.03), or when the nodule was judged to be solitary by palpation (25% vs. 6% for a dominant nodu le in a multinodular goiter, p = 0.02). Bayesian analysis of the data reveals that after an FNA showing a follicular neoplasm, the risk of m alignancy in males with large nodules was nearly 80%, compared with a rate of only 3% in females with small nodules. These results suggest t hat clinical features including gender, nodule size, and character of the gland by palpation can be systematically integrated into the decis ion analysis, thereby improving the selection of patients for surgical referral.