Usually papillary microcarcinoma (PMC) grows very slowly with a good prognosis, although it frequently metastasizes to regional lymph nodes and shows multiple tumor formation in the thyroid. Therefore, how to treat papillary microcarcinoma has been controversial. Recently several studies reported that some ultrasonographic features may potentially reflect the biological aggressiveness of a lesion. We investigated which ultrasonographic findings can reflect aggressive characteristics and whether US can helpful in selecting the appropriate surgical treatment of PMC.

We retrospectively reviewed the preoperative ultrasonographic findings and pathologic risk factors of 68 patients who had undergone surgical treatment for PMC at the Wallace Memorial Baptist Hospital from January 2004 to December 2005.

The incidences of multifocality, extrathyroidal extension, and lymph node metastasis of PMC were 42.6%, 48.5% and 20.6%, respectively. The Mean sizes of PMC were no significant differences according to age, multifocality, extrathyroidal extension, lymph node metastasis, stage and AMES risk group, and tumor size more than 5 mm was not linked to pathologic prognostic factors. Cases demonstrating multiple nodules in the unilateral or bilateral lobes, as well as those with fine strong calcifications in the tumor on US, were directly linked to multifocality on pathologic finding. US is insensitive technique for detecting lymph node metastasis and it's sensitivity was only 14.3%, but it's positive predictive value and specificity were high (100%).

The date suggested that complete surgery with appropriate nodal dissection should be performed in patients with PMC which their US demonstrating multiple nodules in the unilateral or bilateral lobes, fine strong calcifications echoes in tumor and US-detected node metastasis.