RISK OF MALIGNANCY MAY BE HIGHER IN CYTOLOGICALLY SUSPICIOUS THYROID NODULES THAT ARE SMALLER OR MULTIPLE

(medullary thyroid carcinoma, lymphoma, atypia). The malignancy rate was 15% for cytology that was suspicious for follicular and Hurthle-cell lesions and 77% for those suspicious for PTC. Age, elevated levels of thyrotropin (TSH), and history of radiation exposure were not associated with increased malignancy risk. Although the authors state that smaller nodules measured by ultrasonography had a higher risk of malignancy (2.6±1.8 vs. 2.9±1.6 cm; P = 0.008), 34% of nodules >4 cm were malignant. Multiple nodules, as compared with a single nodule, had a higher risk of malignancy (41.1% vs. 26.4%; P = 0.014). In patients with cytology suspicious for follicular and Hurthlecell neoplasm, malignancy risk was higher in those who were undergoing thyroid hormone therapy than in those who were not (37.7% vs. 16.5%; P = 0.0004; odds ratio, 3.0), but the TSH values did not differ significantly between the thyroxine users and nonusers. CONCLUSIONS The risk of malignancy is higher in patients with nodules that are cytologically suspicious for Hurthlecell or follicular neoplasms or PTC when the index nodule is smaller or if the patient has multiple thyroid nodules. This study demonstrates an increased risk of malignancy in patients using thyroid hormone therapy but the reason for this is unknown. SUMMARY BACKGROUND Fine-needle aspiration biopsy (FNAB) has a high predictive value for benign and malignant thyroid nodules but has a lower predictive value for indeterminate or suspicious nodules. Clinical data was extracted from an electronic medical record from January 2004 through September 2008 of patients who had undergone FNAB and thyroid surgery for cytologically suspicious nodules. METHODS AND RESULTS This was a retrospective chart review study at a single referral center, the Mayo Clinic. Review of the electronic medical records revealed that 573 (8%) of 7039 FNAB samples had a suspicious cytologic diagnosis. Of these patients, 111 did not have surgery and did not return for reevaluation. The remaining 462 patients with a suspicious biopsy underwent thyroid surgery. The demographic and clinical characteristics of this group are as follows: 69% female; mean (±SD) age, 53.7±15.2 years; prior head and neck radiation, 5.4%; multiple nodules, 65%; mean nodule size, 2.8±1.7 cm; and thyroid hormone therapy, 19.5%. Of these patients, 326 had lesions suspicious for follicular neoplasm or Hurthle-cell neoplasm, 126 were suspicious for papillary thyroid carcinoma (PTC), and 10 were suspicious for other neoplasms