ABSTRACT
PURPOSE: High resolution ultrasonography has made it possible to detect many non-palpable small nodules in thyroid gland. We investigated the prevalence and clinical features of non-palpable thyroid nodule and carcinoma discovered incidentally at screening ultrasonography in healthy women. METHODS: A retrospective review was undertaken on the previous healthy asymptomatic 1, 714 women where selected to undergo screening ultrasonography for the detection of the presence of non-palpable thyroid nodules from January 2004 to December 2004. The aims of study were to define the prevalence of thyroid nodule and carcinoma in healthy asymptomatic women and to access the extent of disease in patients with malignant nodule by surgery. RESULTS: Of the 1, 714 subject, thyroid nodule were detected in 822 (48.0%) women with their prevalence increasing with the increasing age of patients. The malignant detection rate based on the USG-guided fine-needle aspiration (USGFNA) results, including both suspicious and malignant groups, was 2.8% (48/1, 714) of all subjects. 38 of 50 patients with malignant, suspicious or indeterminate cytology underwent surgery and all of them were confirmed to have papillary carcinoma on histological results. In 38 patients with papillary thyroid carcinoma, the average size of tumors was 0.87+/-0.33 cm, a range of 0.3 to 1.5 cm, multifocal tumors were found in 50% (19/38), bilaterality was found in 44.7% (17/38), extrathyroidal extension was observed in 50.0% (19/38), and regional lymph node metastasis was found in 29.4% (5/17). CONCLUSION: High resolution ultrasonography detected a high percentage (48%) of nonpalpable thyroid nodules. Characteristics of thyroid nodules on ultrasonography can be used to decision of optimal management strategies. Total thyroidectomy with lymph node dissection may be suitable in patients with non-palpable papillary thyroid carcinoma due to its high incidence of extrathyroidal extension, bilaterality and regional lymph node metastasis.