Hashimoto's thyroiditis and papillary thyroid carcinoma. Are cytokeratin 19 and P63 proteins of any diagnostic value?

BACKGROUND: The relation between Hashimoto's thyroiditis (HT) and papillary thyroid carcinoma (PTC) remains controversial. We aimed to study the coexistence of PTC and HT and the diagnostic utility of cytokeratin19 and P63 proteins expression in all positive for PTC cases of HT.

SUBJECTS AND METHODS: We analyzed data from 343 patients who underwent fine needle aspiration cytology followed by thyroid surgery over a six years period. Thyroid scans and blood measurements for anti-thyroid peroxidase antibodies (TPOAb), thyroid stimulating hormone (TSH), anti-thyroglobulin antibodies (TgAb) and free thyroid hormones were performed. We assessed the expression of monoclonal antibodies against cytokeratin 19 (CK19) and factor P63 in all positive for PTC patients.

RESULTS: Hashimoto's thyroiditis was diagnosed by histology in 93 patients. They were: 90 female and 3 male patients. Both HT and PTC were present in 6 female patients (6,7%). All their thyroid scans showed heterogeneous distribution of the tracer with a cold nodule. Laboratory examination showed high levels of TSH as well as of TPOAb in all PTC patients. Cytokeratin 19 showed positive expression in all PTC patients, whereas P63 showed focal positivity in 4/6 cases. We did not estimate the duration of HT in our study.

CONCLUSION: This study showed that 6,7% of female patients with HT also had PTC and all had elevated serum TSH, which may be a risk factor for PTC. The age of PTC patients was between 19-42 years.