Risk factors for malignancy of thyroid nodules initially identified as follicular neoplasia by fine-needle aspiration: Results of a prospective studyof one hundred twenty patients

Indeterminate or suspicious findings on fine-needle aspiration (FNA) of nod ular thyroid disease (i.e., findings that neither give immediate indication for surgery nor lead to clear-cut conservative management) have been the k ey diagnostic problem in thyroid cytology for which the inability to differ entiate cytologically benign from malignant follicular growth has been one reason. The aim of this cohort study of 120 consecutive (103 females, 17 ma les) patients with palpable nodular thyroid disease diagnosed as follicular neoplasia (FN) by FNA (defined by the triad of high numbers of follicular cells, microfollicular arrangement, and scanty or absent colloid) was to id entify patients at high risk for malignancy based on the prospective evalua tion of clinical features and to characterize the histologic entities of FN . Based on a 100% surgery rate we found an 18% malignancy rate (12 papillar y carcinomas, 9 follicular carcinomas). Previously suggested factors with e levated risk for malignancy such as extremes of age, male gender, and large nodule size were not associated with increased risk as were cold nodules b y Tc-99m-scintigraphy (relative risk: 1.2, 95% confidence interval [CI] 0.4 -3.3). However, hard lesions to palpation (relative risk 2.6, 95% CI: 1.2-5 .6), solitary (relative risk: 2.6, 95% CI: 1.7-4.0), and hypoechoic FNs (re lative risk: 3.4, 95% CI: 2.05.7) by ultrasound showed elevated risks of ma lignancy. In summary, suspicious palpation or ultrasound results may help t o define a subgroup of patients with elevated risk of malignancy when FNA i ndicates the diagnosis of follicular neoplasm of the thyroid.