Clinicopathologic features and risk factors for lymph node metastasis of papillary thyroid carcinoma with chronic lymphocytic thyroiditis

Objective To summarize clinicopathologic features of papillary thyroid carcinoma (PTC) coexistent with chronic lymphocytic thyroiditis (CLT) and investigate risk factors for lymph node metastasis. Methods The medical records of 4 264 consecutive papillary thyroid carcinoma patients who received surgical treatment from Oct 2013 to Oct 2015 in Peking Union Medical College Hospital were reviewed. The diagnoses was confirmed by histopathological tests. Univariate analysis was performed to identify specific clinicopathologic features of PTC with CLT. Univariate and multivariate analysis were performed to determine whether each clinicopathologic feature was an independent risk factor for lymph node metastasis. Results In all 4 265 cases, there were 3 059 papillary thyroid microcarcinoma (PTMC) (71.7%) , 1 010 PTC patients (23.7%) with CLT. 909 female patients (90%) , 624 cases with multifocal lesions (61.8%) , 422 cases with extra-thyroid extension (41.8%) , 429 cases with lymph node metastasis (42.5%) , and 133 cases with metastatic lymph nodes (LNs) ≥6 (13.2%) . The median age was 43 years old and median tumor size was 0.8 cm. Patients with CLT were more females (90.0% vs. 70.2%; P 0.05) . In multivariate analysis, CLT was an independent protective factor for lymph node metastasis (OR =0.713, 95% CI 0.609 -0.835, P< 0.001) . In PTC patients with lymph node metastasis, CLT was not associated with lymph node metastasis number (3 vs. 3, P = 0.300) . Conclusions Chronic lymphocytic thyroiditis was an independent protective factor for papillary thyroid carcinoma patients with lymph node metastasis. But in patients with lymph node metastasis, the metastatic number didn't decrease. Key words: Thyroid neoplasms; Carcinoma, papillary; Chronic lymphocytic thyroiditis; Lymph node metastasis