Appropriate treatment for asymptomatic papillary microcarcinoma of the thyroid.

Since the 1990 s, asymptomatic papillary microcarcinoma (PMC), papillary carcinoma measuring <or= 1.0 cm, has frequently been detected using ultrasonographic screening and diagnosed by ultrasonography-guided fineneedle aspiration biopsy. Thyroid carcinoma was detected in 3.5% of otherwise healthy women aged >or= 30 years of age and most of these patients had lesions measuring <or= 1.5 cm in diameter, which is not discrepant with previous autopsy findings that latent PMC showed a high incidence. A recent observation trial showed that only 6.7% of low-risk PMC definitely became enlarged during 5 years of follow up, indicating that observation is an attractive alternative to surgery for PMC. However, PMC with clinically apparent metastasis detected on imaging is likely to show a recurrence to the lymph node and careful neck dissection as well as total thyroidectomy may be required. If surgical treatment is performed for low-risk PMC, prophylactic modified radical neck dissection is not necessary and lobectomy (with isthmectomy) and central node dissection is adequate if the tumor is located only in one lobe.