Preoperative ultrasonographic examination for lymph node metastasis: usefulness when designing lymph node dissection for papillary microcarcinoma of the thyroid.

Papillary microcarcinoma has an excellent prognosis after surgical treatment, but how to dissect the lymph nodes remains an open question. In this study, we investigated whether modified radical neck dissection (MND) affected the lymph node recurrence-free survival (LN-RFS) rate for 590 patients with papillary microcarcinoma and recurrence in the lateral compartment who underwent surgery in our hospital between 1993 and 2001. MND was performed in 316 patients, and metastasis in lateral compartment was preoperatively detected on ultrasonography in 67. These 67 patients showed significantly worse LN-RFS (p = 0.0038) than the remaining 249 patients without preoperatively detectable lateral node metastasis. Of the 523 patients (590 minus the 67 patients) whose lateral node metastasis was not detected preoperatively, 249 underwent MND; the remaining 274 patients did not. There was no significant difference in LN-RFS between these two groups. Our preliminary data suggest that with papillary microcarcinoma: (1) MND is not necessary in patients without lateral node metastasis detected on ultrasonography preoperatively, and (2) patients with preoperatively detected lateral node metastasis are more likely to develop recurrence in the lymph nodes so careful MND should be performed.