Coexistence of papillary carcinoma and Hashimoto's thyroiditis.

The aim of the study was to determine the incidence of coexistence of papillary carcinoma and Hashimoto's thyroiditis in cytologic material. Cytologic findings were collected from 10508 patients that underwent ultrasound-guided fine needle aspiration cytology (FNAC) of the thyroid. Hashimoto's thyroiditis was found in 2156 (20.5%) and papillary carcinoma in 269 (2.6%) of 10508 patients with FNAC, whereas both Hashimoto's thyroiditis and papillary carcinoma were present in 42 (0.4%) patients. Among patients with FNAC diagnosis of Hashimoto's thyroiditis, the prevalence of papillary carcinoma was 1.9%. Among patients with FNAC diagnosis of papillary carcinoma, the prevalence of Hashimoto's thyroiditis was 15.6%. There was no statistically significant association between the presence of papillary carcinoma and Hashimoto's thyroiditis in patients undergoing FNAC (p=0.0522). In conclusion, in a large series of patients, the incidence of Hashimoto's thyroiditis and papillary carcinoma coexistence in cytologic material was 0.4%. There was no statistically significant relationship between Hashimoto's thyroiditis and papillary carcinoma in cytologic material.