Clinicopathological features and treatment of postsurgical incidental papillary thyroid microcarcinoma

Objective To analyze clinicopathologic features and treatment strategy of postsurgical incidental papillary thyroid microcarcinoma(PTMC). Methods A total of 305 patients undergoing surgery for thyroid diseases from Apr. 2012 to Mar. 2013 were retrospectively analyzed. Results Among the 305 patients, 19 patients(18 females and 1 male)showed PTMC incidentally after surgery. The mean age was(43.2±12.8)years(ranging from 23 to 67 years old). All patients underwent subtotal thyroidectomy, including 17 endoscopic surgery and 2 open surgery. All frozen sections were benign during operation while pathologic results were PTMC after surgery. The average size of tumors was(2.2±1.5)mm which all was unicentric with no lymph node enlargement intraoperatively. Immunohistochemistry showed that the positive rate of cytokeratin 19, galectin-3, mesothelial cell, and CD56 was 87.5%, 43.8%, 81.3% and 18.8%, respectively. There were 4 cases of B-raf V600E mutation found in 6 patients. All patients discharged 1 to 3 days after surgical treatment with no complication and received levothyroxine therapy with a suppressive dose of thyrotropin(TSH). 131I therapy was not given. Conclusions PTMC is found more common in female and younger age under 45 years. Tumor is usually unicentric and less than 5 mm. Lymph node metastasis is rare. Immunohistochemistry and B-raf V600E mutant test can help the diagnosis. Initial endoscopic subtotal thyroidectomy is effective. There is no need of further surgery and 131I therapy. Key words: Thyroid; Papillary Microcarcinoma; Postsurgical incidental papillary thyroid microcarcinoma