Clinicopathological characterization and prognostic implication of FOXP3 and CK19 expression in papillary thyroid carcinoma and concomitant Hashimoto's thyroiditis

Papillary thyroid carcinoma (PTC) is considered the most prevalent thyroid malignancy. The association between Hashimoto’s thyroiditis (HT) and PTC is still unclear. We aimed to examine the clinicopathological impact of immunohistochemical staining of FOXP3 and Cytokeratin 19 in PTC and concomitant HT and their correlation with patients' outcome and survival. Eighty thyroid biopsies obtained from patients with PTC were immunostained by FOXP3 and CK19.The patients were treated by radioactive iodine (I 131 ) and followed up. FOXP3 and CK19 expression were detected in 45% and 80% studied cases of PTC respectively. 16.7% of PTC with associated HT showed FOXP3+ lymphocytes in lymphocytic infiltrate of HT, while most of PTC associated HT express cytoplasmic CK19 positive Hurtle cells. FOXP3 was more expressed in PTC female patients more than 45 years with higher stage, lymph node, and distant metastasis, extracapsular extension, number of I 131 doses, and cumulative radioiodine doses with a highly statistically significant difference (p