ECE2016 Guided Posters Thyroid Cancer (1) (10 abstracts)
1Yildirim Beyazit University, Ataturk Education and Research Hospital, Endocrinology and Metabolism Department, Ankara, Turkey; 2Yildirim Beyazit University, Ataturk Education and Research Hospital, Pathology Department, Ankara, Turkey; 3Yildirim Beyazit University, Ataturk Education and Research Hospital, General Surgery Department, Ankara, Turkey.
Background: We aimed to evaluate malignancy rate in thyroid nodules ≥4 cm and determine false negativity of fine needle aspiration biopsy (FNAB) in these nodules.
Methods: Patients who underwent thyroidectomy between January 2007 and December 2014 in our institution were reviewed. Demographical and clinical data and preoperative ultrasonography (US) findings were obtained from the medical records. The nodules in these patients were grouped as ≥4 cm and <4 cm according to US measurements. Nodules <4 cm were further divided into 13.9 cm and <1 cm. US features and malignancy rates were compared. Histopathologically malignant nodules with preoperative benign cytology were defined to have false negative FNAB.
Results: Data of 5561 nodules in 2463 patients were analyzed. There were 1008 nodules ≥4 cm, 4013 nodules 13.9 cm and 540 nodules <1 cm. Histopathologically, 8.5, 10.2 and 25.6% of nodules ≥4 cm, 13.9 cm and <1 cm were malignant, respectively (P<0.001). There was no significant difference between the 13.9 cm and ≥4 cm nodules with respect to malignancy (P=0.108). Preoperative US features were similar in histopathologically benign and malignant nodules ≥4 cm, except higher prevalence of hypoechoic appearance in malignant ones (P=0.02). False negativity rates were 4.7% (32/683) in ≥4 cm, 2.2% (45/2093) in 13.9 cm and 4.8% (10/206) in <1 cm nodules. <1 cm and ≥4 cm nodules had similar false negativity (P=0.93), while 13.9 cm nodules had statistically lower false negativity than both groups (P=0.03 and P<0.001, respectively).
Conclusion: Malignancy rate in thyroid nodules ≥4 cm is similar with nodules 13.9 cm. Although false negativity of FNAB was significantly higher in ≥4 cm than 13.9 cm nodules, the rate was 4.7% which we think not high enough to recommend routine surgery when cytology was benign.