Table 1.

Contraindications for the Active Surveillance of PMCs

Type	Contraindications
Clinical high-risk features	1. N1 (may present on imaging studies) or M1 (very rare) 2. Signs or symptoms of invasion to the recurrent laryngeal nerve or trachea 3. High-grade malignancy on cytology (very rare) 4. Cases showing progression signs such as size enlargement or a novel appearance of lymph node metastasis during active surveillance
Features unsuitable for observation, although it is unclear whether they are associated with biological aggressiveness	Imaging studies indicate that the tumor may invade the trachea or recurrent laryngeal nerve

PMC, papillary microcarcinoma.