Risk of lymph node metastases in multifocal papillary thyroid cancer associated with Hashimoto's thyroiditis

The aim of this study was to evaluate the risk factors of lymph nodes metastases (LNM) in patients with papillary thyroid cancer (PTC) and coexisting Hashimoto's thyroiditis (HT). This was a retrospective cohort study of patients with PTC and HT who had undergone total thyroidectomy (TT) with central neck dissection (CND) over an 11-year period (between 2002 and 2012). Pathological reports of all eligible patients were reviewed. Multivariable analysis was performed to identify risk factors of LNM. During the study period, PTC was diagnosed in 130 patients with HT who had undergone TT with CND (F/M ratio = 110:20; median age, 52.4 +/- 12.7 years). Multifocal lesions were observed in 28 (21.5 %) patients. LNM were identified in 25 of 28 (89.3 %) patients with multifocal PTC and HT versus 69 of 102 (67.5 %) patients with a solitary focus of PTC and HT (p = 0.023). In multivariable analysis, multifocal disease was identified as an independent risk factor for LNM (odds ratio, 3.99; 95 % confidence interval, 1.12 to 14.15; p = 0.033). Multifocal PTC in patients with HT is associated with an increased risk of LNM. Nevertheless, the clinical importance of this finding needs to be validated in well-designed prospective studies.