Papillary thyroid microcarcinoma: clinical and pathological study of 321 cases.

The primary aim of the study was to investigate microcarcinoma characteristics of aggressivity, multicentricity and metastasis. Though its features are not significantly different from those of other papillary carcinomas, the optimal therapeutic approach continues to be an issue of controversy, most notably appropriate surgical approach and indications for neck dissection. The study is retrospective analysis of 321 microcarcinoma cases, operated upon with total thyroidectomy, with or without neck dissection. These cases were compared to larger papillary cancers. We found that 35.1% tumors were aggressive; 25.2% were multicentric, with foci in the contralateral lobe nearly twice as often as in the ipsilateral lobe; and 18.2% were metastatic. In comparison to groups of < or = 2 cm and < or = 3 cm, microcarcinomas were less aggressive, multicentric and metastatic. Male gender and age < 45 were unfavorable parameters. Multivariate analysis revealed contralateral lobe multicentricity and male gender as risk factors for metastasis. Although microcarcinoma demonstrated better characteristics than larger tumors, this subgroup behaves aggressively and should be approached cautiously.