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Purpose Lymph node metastasis in papillary thyroid cancer (PTC) occurs 40–60%. Extrathyroidal extension and large tumor size are most reliable predicting factors for central lymph node metastasis whose prognostic value is controversial. In this study, we evaluated the relationship between a specific finding of primary tumor in the thyroid, fibrosis, and negative prognostic factors. Materials and methods We reviewed the patients who underwent total thyroidectomy and central lymph node (CLN) dissection with or without lateral lymph node dissection (LND) for PTC, from January to December, 2011. We defined (+) finding when the degree of fibrosis comprises 10% or more of the primary tumor. Correlation between degree of fibrosis and negative prognostic factors, including age, gender, tumor size, extrathyroidal extension (ETE), number of CLN metastasis, and lateral cervical lymph node metastasis (LCLNM), was analyzed. Results Of the 481 patients, fibrosis (+) group includes 387 patients (80.5%). On the chi-square test, age, gender, tumor size, and LCLNM were not correlated with fibrosis. ETE (+) group comprised of higher rate of fibrosis (+) group (90.4%) compared to ETE (−) group (64.9%, p Conclusions Fibrosis in PTC can be a risk factor of extrathyroidal extension, a negative prognostic factor. This suggests that the behavior of fibrotic tumor is, possibly, more aggressive than non-fibrotic tumor.

Purpose Although prognostic significance of central lymph node (CLN) metastasis in micropapillary thyroid cancer (microPTC) is controversial, thorough removal of metastatic lymph nodes may reduce the recurrence rate. Histological or clinical predicting factors for CLN metastasis have been studied to determine the adequate surgical extent or postoperative adjuvant therapy to eradicate metastatic lymph nodes. However, histological features inside primary tumor were not considered as a predicting factor for metastasis. In this study, we evaluated the relationship between specific findings of microPTC and central lymph node metastasis. Materials and methods We reviewed the patients who underwent total thyroidectomy and central lymph node (CLN) dissection for microPTC, from January to December, 2011. Growth pattern, fibrosis, and architecture of tumors were used as histological factors. Fibrosis was classified into three groups; I Results Of the 353 patients, 162 had CLN metastasis (45.9%). Chi-square test showed that age, gender, and tumor size were not related to CLN metastasis. Group I ( n = 55) had lower rate of CLN metastasis (30.9%) than group II (35.5%) and group III (64.3%, p = 0.043). Group A ( n = 28) had lower rate of CLN metastasis (14.3%) than group B (18.2%) and group C (39.8%, p = 0.019). Multivariate analysis showed that growth pattern was only risk factor for CLN metastasis (odds ratio = 1.972, p = 0.022). Conclusions Follicular or infiltrative growth pattern of intraparenchymal microPTC is an independent risk factor for CLN metastasis This report suggests that tumor behavior in the primary tumor plays a important role in CLN metastasis.