[Clinicopathological features of thyroid papillary microcarcinoma of which the maximum diameter is less than 5 mm: a series of 487 cases]

Objective: To analyze the clinical and pathological features of papillary thyroid microcarcinoma(PTMC) of which the maximum diameter is less than 5 mm. Methods: Clinical data of 487 PTMC (≤5 mm) patients who underwent primary surgery by the same team of doctors between March 2013 to March 2016 at Department of Surgery, Ruijin Hospital, School of Medicine, Shanghai Jiaotong University were analyzed retrospectively. Female patients accounted for 77.4%(377/487). The age ranged from 22 to 80 years, with an average of (46±11) years.χ² test and multivariate Logistic regression analysis were used to analyze risk factors. Results: There were 93.6% (456/487) of the patients with preoperative definite diagnosis. There were 92.6% (452/487) of the patients underwent unilateral thyroid lobectomy with isthmectomy and ipsilateral central lymph node dissection. Multifocal carcinoma accounted for 20.3% (99/487), Ⅲ to Ⅳ phase cases accounted for 12.3% (60/487), patients with low risk of recurrence accounted for 67.6% (329/487). The central lymph node metastasis rate was 34.9% (170/487). Male (OR=2.149, 95%CI: 1.367 to 3.381), age<45 years (OR=0.451, 95%CI: 0.303 to 0.672), multifocal carcinoma (OR=1.798, 95%CI: 1.116 to 2.898), and capsular invasion (OR=3.678, 95%CI: 1.406 to 9.622) were the independent risk factors for lymph node metastasis (P<0.05). Conclusion: Regardless of tumor size, PTMC still needs to be taken seriously, especially male, age < 45 years, capsular invasion, or multifocal carcinoma patients.