OBJECTIVETo compare the size of papillary thyroid carcinoma on ultrasonography(US)and the actual size measured during histological examination and to discuss the potential causes of such discrepancy.

METHODSA total of 148 patients with histologically confirmed papillary thyroid carcinoma underwent thyroid surgery in our center from December 2012 to May 2013. Patients were stratified based on the size,morphology,margin,cystic component,and presence of Hashimoto's disease to compare the discrepancy of the US and pathalogical measurements.

RESULTSThe mean sizes of the nodules measured by US and pathology were(1.58±0.94)cm and(1.33±0.84)cm,respectively(P=0.000). In 70.9%(105/148)of the nodules,the sizes measured by US were larger than those measured by pathology. In 17.6%(26/148)of the nodules,the sizes measured by US were smaller than those measured by pathology. In 1.1-1.4 cm size subgroup,the difference between mean ultrasound diameter and pathologic diameter was not significant [(1.21±0.11)cm vs.(1.11±0.32)cm,P=0.062]. In 0.1-1.0 cm size subgroup,the mean sizes of the nodules measured by US and pathology were(0.75±0.19)cm and(0.62±0.23)cm,respectively(P=0.000). In ≥1.5 cm size subgroup,the mean sizes of the nodules measured by US and pathology were(2.48±0.70)cm and(2.03±0.81)cm(P=0.000).

CONCLUSIONSThere is a significant discrepancy between US and pathologic size measurements for papillary thyroid carcinoma. However,for nodules sized 1.1-1.4 cm,the ultrasound and pathologic measurements are more likely to be consistent.