OP100 – The Impact of Hashimoto Thyroiditis on Lymph Node Yield and Metastatic Lymph Node Ratio in Thyroid Malignancy

      Mohsin, Khuzema1;  Murcy, Mohammad1; Mohamed, Hossam1; Hassoon, Taha1;  Al-Qurayshi, Zaid2;  Monlezun, Dominique3; Kandil, Emad1 1 Division of Endocrine and Oncological Surgery, Tulane University School of Medicine, New Orleans, United States 2 Department of Otolaryngology–Head & Neck Surgery, University of Iowa Hospitals and Clinics, Iowa City, United States 3 Department of Global Health Management & Policy, Tulane University School of Public Health and Tropical Medicine, New Orleans, United States   Background/Purpose: A number of studies have reported the association between thyroid cancer (TC) and Hashimoto’s thyroiditis (HT). However, the impact of HT on the number of dissected lymph nodes in each surgery, referred to as lymph node yield (LNY), or the proportion of these dissected lymph nodes with malignant pathology, referred to as lymph node ratio (LNR), remains uncertain. We aim to evaluate this correlation. Methods: A retrospective review of thyroid surgery caes at a single U.S. institution over a 5-year period. Patients were divided according to the occurrence of HT into 2 groups: HT and non-HT patients. Patients were evaluated for demographic data, presence of malignancy, histological type of malignancy, size of the tumor, presence of multi-focal disease, existence of lymph node metastasis, LNY, LNR and BRAF gene mutation status. Results: 1635 patients were included, HT was diagnosed in 349 (34%) of them. Patients with HT were more likely to have TC [141 (40.87%)] than Non-HT patients [352 (27.63%), p<0.001]. However, HT patients were less likely to have metastatic lymph nodes [14 (20.29%)] than non-HT patients [72 (45.28%), <0.001]. HT patients also had lower LNR [12.40 (21.13)] then non-HT patients [30.59 (34.17), p=0.004]. No difference in LNY was found between HT and non-HT patients (p=0.296). Tumor size, presence of multifocal disease, and BRAF status were similar between both groups. Discussion & Conclusions: Although HT is associated with higher rates of TC, the co-existence of HT with TC is linked with less metastasis than non-HT with TC. Future multi-institutional studies are warranted.   References:
    1. Noureldine, S.I. and R.P. Tufano, Association of Hashimoto’s thyroiditis and thyroid cancer.Curr Opin Oncol, 2015. 27(1): p. 21-5.
    2. Molnar, S., et al., [Clinico-pathological features of papillary thyroid cancer coexistent with Hashimoto’s thyroiditis]. Orv Hetil, 2017. 158(5): p. 178-182.


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