[Lymph node micrometastases of thyroid cancer].

It is not uncommon for micrometastases to be detected in the regional lymph nodes in patients with thyroid cancer. It remains controversial whether lymph node dissection improves patient outcomes. According to the clinical guidelines edited by the Japan Association of Endocrine Surgeons and Japanese Society of Thyroid Surgeons, there is no evidence that prophylactic central compartment dissection improves the cause-specific survival of papillary carcinoma patients. However, it is recommended at initial surgery because reoperation for recurrence in this compartment may induce severe complications. On the other hand, prophylactic lateral node dissection can reduce the risk of recurrence to the nodes and improve disease-free survival rates, although evidence is lacking on whether it improves cause-specific survival. Surgeons should be aware that pathologically identified metastatic lymph nodes are less common than actual metastatic lesions and determine the disease entity of ectopic thyroid tissue in lymph nodes. Recently, useful new techniques such as thyroglobulin measurement of fine-needle aspiration specimens or sentinel lymph node biopsy have become established.