LYMPHOCYTIC THYROIDITIS IS ASSOCIATED WITH INCREASED NUMBER OF BENIGN CERVICAL NODES AND FEWER CENTRAL NECK COMPARTMENT METASTATIC LYMPH NODES IN PATIENTS WITH DIFFERENTIATED THYROID CANCER.

BACKGROUND: Whether or not autoimmune thyroid disease influences progression of differentiated thyroid cancer (DTC) remains controversial. Findings of previous studies are influenced by lead time bias and/or procedure bias selection These biases can be reduced by studying a single-institution patient population that underwent similar extent of surgical resection.

METHODS: From a cohort of 660 patients with DTC who underwent thyroidectomy, we retrospectively studied 357 patients who underwent total thyroidectomy and central compartment node dissection (CCND) for DTC between 2003 and 2013.

RESULTS: Forty-one percent (140/345) of study patients had lymphocytic thyroiditis (LT) and 30% (91/301) had positive serum anti-thyroglobulin antibody (TgAb). LT was reported in 78% of the TgAb-positive cases. Sixty percent (213/357) of cases had metastatic thyroid carcinoma in one or more neck lymph nodes [55% (198/357) central compartment, and 22% (77/356) lateral compartment]. Patients with LT had fewer metastatic cervical lymph nodes than those with no LT (2.7+/-4.7 vs 3.5+/-4.8, respectively, p=0.0285). Patients with positive TgAb and thyroiditis had a larger number of benign cervical lymph nodes removed than those with negative TgAb or no LT. No significant difference was observed in age, tumor size, multifocality, extra-thyroidal extension, vascular invasion or frequency of cervical lymph node metastasis between TgAb-negative and TgAb-positive cases or between cases with and without LT.

CONCLUSIONS: Lymphocytic thyroiditis is associated with fewer central neck compartment metastatic lymph nodes, and with larger number of excised reactive benign cervical lymph nodes Whether this association indicates protective role of thyroid auto-immunity in lymph node spreading remains unclear.