Background: The clinical management of patients with solitary thyroid nodule is well established; however, the evaluation of patients with multiple thyroid nodules is controversial. The aim of this study was to assess if there is a correlation between the risk of malignancy and number of thyroid nodules.
Design: The study cohort included 2,884 patients (2,410 females and 474 males) with 3,274 thyroid nodules that underwent FNA under ultrasound guidance between November 1997 and April 2004. Multiple thyroid nodules were aspirated in 360 patients; 2 in 332 (291 females, 41 males), 3 nodules in 26 (23 females, 3 males), and 4 nodules in 2 patients (1 female, 1 male). Subsequent information regarding the histological diagnosis was obtained in the cases that underwent surgical excision.
Results: The average age for patients with single or multiple nodules was the same (51 yr). The FNA specimens were diagnosed as benign (n = 1,663, 51%), neoplasm (n = 880, 27%), suspicious for neoplasm or papillary carcinoma (n = 234, 7%), malignant (n = 187, 6%), and non-diagnostic (n = 310, 9%). Surgical excision was performed in 1,135 patients: 993 patients with single nodules and 142 patients with multiple nodules. The surgical pathology diagnosis was benign in 656 nodules (52%) and malignant in 596 nodules (48%). In the malignant category 153 tumors were papillary microcarcinoma (<1 cm). Excluding these cases, the malignancy rate was 39% in patients with single nodules, 41% with two nodules, and 21% with three nodules.
Conclusions: The cancer risk is similar for patients with one or two nodules over 1 cm and decreases with three or more thyroid nodules.