Hashimoto's thyroiditis in papillary thyroid carcinoma: a 22-year study

Objective. We retrospectively investigated whether there is a relationship between Hashimoto's thyroiditis (HT) and papillary thyroid carcinoma and studied the effect of HT on prognostic factors. Methods. 1080 patients, who underwent thyroidectomy in our hospital and received a diagnosis of papillary thyroid carcinoma, were included in the study. In histopathological specimens, the diagnosis of papillary thyroid carcinoma was reconfirmed and non-neoplastic areas in the same specimen were evaluated in terms of HT. Results. HT was detected in non-neoplastic areas of specimens in 36.1% (n = 390) of 1080 patients with a diagnosis of papillary thyroid carcinoma whereas HT was not observed in 63.9% (n = 690). There was a significant positive correlation between presence of HT and multifocal location (p < 0.05, chi(2) = 38.5). There was no significant relationship between extrathyroidal tissue invasion and HT (p > 0.05). Conclusion. We assume that patients with HT developing papillary thyroid carcinoma have an increased risk of having multifocal tumour, and thus surgical intervention should be tailored according to this risk.