PURPOSE: Although papillary thyroid microcarcinoma (PTMC) has very excellent prognosis, lymph node metastases are found frequently. This study identifies the risk factors of clinically negative cervical lymph node metastasis (cN0) and investigates the need for central lymph node dissection in cN0 PTMC. METHODS: From Jan. 1(st) 2007 to Dec. 30(th) 2013, 1593 patients received surgery for papillary thyroid carcinoma. Seven hundred and eleven patients were diagnosed with cN0 PTMCs. They all received thyroidectomy (total thyroidectomy or lobectomy) with prophylactic central neck dissection. We reviewed the medical records and analyzed the risk factors affecting central lymph node metastasis (CLNM). RESULTS: Of 711 PTMCs patients without clinical lymph node metastasis, 170 (23.9%) patients had CLNM. CLNM was frequent in males than females (P<0.001). The larger the primary tumor, the higher the risk of CLNM (P<0.001). Extra-thyroidal extension was an independent risk factor of CLNM (P<0.001). Recurrence rates in the CLNM negative group was 1.3%, and in the CLNM positive group 2.4%. The CLNM positive group recurred at a slightly higher rate, but not statistically significantly (P=0.329). Five year disease free survival in the CLNM negative was 96.8%, and in the positive group 94.1%, not a statistically significant (P=0.630). CONCLUSION: In this study, male gender, the size of primary tumor, and extra-thyroidal extension were the risk factors of occult LNM but occult LNM in PTMC was not associated with recurrence rate or five-year disease free survivals. Therefore, we can omit prophylactic central lymph node dissection in patient with cN0 PTMC.
Disease-Free Survival ; Female ; Humans ; Lymph Node Excision* ; Lymph Nodes* ; Male ; Medical Records ; Neck Dissection ; Neoplasm Metastasis ; Prognosis ; Recurrence ; Risk Factors ; Thyroid Gland* ; Thyroid Neoplasms ; Thyroidectomy

PURPOSE: The follicular variant of papillary thyroid carcinoma (FVPTC) is the most common variant of papillary thyroid carcinoma (PTC). Preoperative diagnosis of FVPTC is often confused with cPTC, follicular neoplasm (FN), and benign follicular lesion because of the paucity of nuclear changes of PTC and overlapping features with benign and other neoplastic follicular lesions. The aim of this study is to elucidate whether ultrasonography and/or intraoperative frozen section analysis (FSA) have a supplementary role in the diagnosis of FVPTC. METHODS: Fifty-five patients diagnosed with histologically confirmed FVPTC from January 2007 to December 2013 were identified. All patients had undergone either lobectomy with/without completion thyroidectomy or total thyroidectomy. Medical records, final histological reports and sonographic (US) findings were reviewed. All sonographic images, 53 fine needle aspiration cytology (FNAC) slides, and FSA slides for 24 cases were available for reexamination. RESULTS: Three histologic types of FVPTC were identified: encapsulated (n=39); infiltrative (n=15); and diffuse (n=1). There were two distinct sonographic patterns: FN-type (n=28) and PTC-type (n=27). The encapsulated type is more common in the FN-like pattern, compared to the PTC-like one (85.7% vs. 55.6%, P=0.009). Among the 24 cases in which sonographic images and FNAC and FSA slides were available for review, six cases (25%) were diagnosed as either FN in FNAC and suspicious PTC(R/O PTC)/PTC in FSA or R/O PTC/PTC in FNAC and FN in FSA. Among those 24 cases described above, 13 cases (54.2%) were diagnosed as either FN-type in US and R/O PTC/PTC in FNAC/FSA or PTC-type in US and FN in FNAC/FSA. CONCLUSION: It is difficult to make a correct diagnosis of FVPTC before definitive treatment even with US, FNAC and FSA. However the possibility of FVPTC must be considered, especially when diagnoses in US, FNAC and FSA are different and include R/O PTC/PTC and FN in the same case.
Biopsy, Fine-Needle ; Diagnosis* ; Frozen Sections* ; Humans ; Medical Records ; Thyroid Gland* ; Thyroid Neoplasms* ; Thyroidectomy ; Ultrasonography*