Sonographic characteristics suggesting papillary thyroid carcinoma according to nodule size.

Purpose: To determine differences in ultrasonography (US) features suggesting papillary thyroid carcinoma (PTC) between nodules larger than 10 mm (large lesions) and nodules ≤10 mm in diameter (small lesions).

Methods: We included 1,238 nodules in 1,173 patients that were confirmed through cytology or histopathology between February 2007 and June 2007 in the study. Nodules were divided into large lesions (571 lesions) and small lesions (667 lesions). Sonographic features were defined as composition, echogenicity, margin, calcifications, shape, and vascularity. Logistic regression analyses were performed to determine the odds ratios (OR) of each feature to predict PTC.

Results: On multivariate analysis, irregular margin (OR = 37.788, P < 0.001), microcalcifications (OR = 17.799, P < 0.001), microlobulated margin (OR = 10.385, P < 0.001), and no vascularity (OR = 5.975, P < 0.001) were independent factors for PTC in the large lesions and irregular margin (OR = 7.185, P < 0.001), microlobulated margin (OR = 5.952, P < 0.001), microcalcifications (OR = 3.722, P < 0.001), marked hypoechogenicity (OR = 2.873, P = 0.004), and taller than wide shape (OR = 2.698, P < 0.001) were independent factors for PTC in the small lesions.

Conclusions: The OR of each US finding for predicting PTC is different between large and small lesions. Therefore, it would be helpful to weight certain US features according to nodule size when reporting thyroid nodules with different risks of PTC.