The impact of the multifocality and subtypes of papillary thyroid carcinoma on central compartment lymph node metastasis.

OBJECTIVE: Papillary thyroid carcinoma (PTC) may often appear as multifocal disease. Few studies demonstrated a higher rate of central compartment lymph node metastasis (CCLNM) in multifocal PTC patients. Therefore, the effect of different histological subtypes of multifocal PTC on CCLNM is another subject for further examination. The aim of the present study is to evaluate the rate of central lymph node positivity in multifocal PTC as compared to unifocal disease, and to identify the role of different histologic subtypes of PTC on central neck lymph node positivity.

PATIENTS AND METHODS: Patients with PTC who underwent total thyroidectomy (TT) + central cervical lymph node dissection (CCLND) at authors' institution between January 2012 and June 2016 were included (n=274). Independent Samples t-test, Mann-Whitney U test and Chi-square tests were used to determine univariate associations, and multivariate analysis was conducted by logistic regression.

RESULTS: The rate of CCLND positivity in multifocal PTC is higher than unifocal tumors and the difference is significant (p < 0.05). The univariate analysis demonstrated significant relation with male sex, lymphovascular invasion and size of dominant nodule > 10 mm regarding of CCLND positivity in multifocal PTC patients. The comparison between solitary and mixed histologic subtype of multifocal PTC is also significant (p < 0.05).

CONCLUSIONS: Multifocality is an important risk factor for CCLNM. Male sex, dominant tumor size >10 mm and mixed histological subtype in multifocal PTC may play an important role in CCLND positivity.