The recent prevalence of ultrasound-guided fine-needle aspiration biopsy has resulted in a marked increase in the number of patients with papillary microcarcinoma (maximum diameter,

We previously demonstrated that (1) most papillary microcarcinomas can be followed without surgical treatment and (2) when surgery is performed, patients with lateral lymph node metastasis detected on preoperative ultrasonography (US) are more likely to develop recurrence. In this study, we further investigated the application of these strategies. To date, we have observed 211 patients (average follow-up 47.9 months). In more than 70% of these patients the tumor size did not increase during the follow-up period. There were no clinicopathologic features linked to tumor enlargement except in tumors > or = 7 mm, which tended to enlarge in patients followed for 4 years. To evaluate not only whether observation can continue but also how to dissect the lymph nodes optimally at surgery, US diagnosis for lateral node metastasis is essential because the presence of US-diagnosed lateral metastasis is an even stronger predictive marker for recurrence than the presence of pathologically confirmed node metastasis. The positive predictive value (PPV) was 80.6% for US but reached 100% if fine-needle aspiration biopsy (FNAB) of nodes or FNAB-thyroglobulin measurement is added. Furthermore, carcinomas occupying the upper region of the thyroid more frequently showed US-diagnosed and pathologically confirmed lateral metastasis, and those measuring > or = 7 mm were more likely to show pathologically confirmed lateral metastasis. These findings suggest that, for papillary microcarcinoma: (1) US-diagnosed lateral metastasis is a strong marker predicting a worse relapse-free survival; (2) FNAB of nodes and FNAB-thyroglobulin measurement are useful tools for evaluating lymph node metastasis; and (3) careful US evaluation for lateral metastasis is necessary in patients with a tumor measuring > or = 7 mm or that is located in the upper region of the thyroid both during observation and preoperatively.

These findings suggest that (1) upgrading of T category for tumors with massive extension is appropriate, whereas that for tumors with only minimal extension is not, and (2) careful surgical treatment and postoperative follow-up are required for tumors with massive extension to posterior organs other than the recurrent laryngeal nerve.

We previously demonstrated that for papillary microcarcinoma (PMC), (1) patients with lateral lymph node metastasis detected on preoperative ultrasonography (US) are more likely to develop recurrence, and (2) dissection of the lateral compartment does not improve the prognosis of patients without US-detectable lateral metastasis. In this study, we focused on metastasis from PMC to the central compartment. We investigated the clinical significance of lymph nodes in the central compartment using the same series of 600 patients as used in the previous study. Ultrasound-diagnosed central node metastasis could be found in 30 patients (20.0%). Although the specificity of US for detecting central node metastasis was 99.1%, sensitivity was only 10.9%. Neither US-diagnosed nor pathologically confirmed central node metastasis affected the disease-free survival (DFS) rate of PMC patients. Furthermore, in cases where PMC was located only in one lobe, central node dissection in the contralateral lobe did not improve the DFS rate. These findings suggest that, for PMC, (1) US is an insensitive technique for detecting the central node metastasis, (2) the presence of central node metastasis is unrelated to DFS of patients, and (3) when performing lobectomy for PMC involving only one lobe, dissection of the central compartment in the contralateral lobe is optional.

Prophylactic MND is recommended for cases of papillary carcinoma demonstrating two or more of the following four characteristics; male gender, age 55 years or older, maximal tumor diameter larger than 3 cm, and massive extrathyroid extension.