Association between papillary thyroid carcinoma and lymphocytic thyroiditis: A retrospective study

The aim of the present study was to evaluate the association between coexisting lymphocytic thyroiditis (LT) and the clinicopathological features of papillary thyroid carcinoma (PTC). The records of 458 patients with PTC who underwent a total thyroidectomy and lymph node dissection in Sir Run Run Shaw Hospital (Hangzhou, China) were analyzed. In accordance with the histopathology of thyroid parenchyma, the cases were divided into three groups, including Hashimoto's thyroiditis (HT), non-Hashimoto's type LT (NHLT) and no LT. Based on the histopathology, data on age, sex, maximum diameter of tumor, multifocality, extrathyroidal extension, metastatic lymph node size, extranodal extension and tumor grades in the different groups were analyzed and compared. The prevalence of coexisting LT was 29.0% (133/458), of which 7.6% (35/458) was HT and 21.4% (98/458) was NHLT. PTC concomitant with LT was significantly associated with female patients (95.5 vs. 70.2%; P<0.001), a lower rate of extrathyroidal extension and/or capsular invasion (25.6 vs. 39.7%; P=0.004), central lymph node metastasis (CLNM) ratio (10.71 vs. 17.37; P=0.014), higher number of dissected central lymph nodes (16.83 vs. 11.7; P<0.001), larger metastatic lymph nodes (0.66 vs. 0.46 cm; P<0.001), higher occurrence of multifocality (61.7 vs. 50.5%; P=0.029) and earlier pT stage (57.9 vs. 38.8%; P<0.001), regardless of the combined or separate consideration of HT and NHLT. Besides, LT was associated with multifocality [odds ratio (OR), 1.578; 95% confidence interval (CI), 1.046-2.382; P=0.030]. Furthermore, in patients with PTC, CLNM had a significant association with the male sex (OR, 2.000; 95% CI, 1.216-3.288; P=0.006), an age of <45 years (OR, 0.592; 95% CI, 0.398-0.879; P=0.009) and a tumor size of >1 cm (OR, 3.913; 95% CI, 2.431-5.734; P<0.001). In conclusion, patients with PTC and LT showed a greater female preponderance, multifocality, a lower extrathyroidal extension and a lower CLNM ratio. LT was associated with an increased risk of multifocality in PTC.