Intriduction: The reported prevalence of chronic autoimmune thyroiditis associated with differentiated thyroid cancer (DTC) is heterogeneous.The aim of this study was to evaluate some epidemiological, clinical, sonographical and histological features of operated thyroidnodules with background diffuse autoimmune thyroiditis.

Material and methods: The study included 411 cases with Hashimoto’s thyroiditis (HT), of which 118 presented thyroid nodular disease(TND). Thyroidectomy was performed in 76 cases. Of these patients, 24 presented histologically confirmed DTC and 52 benign lesions.DTC types were as follows: papillary thyroid cancer (PTC) (n = 6), follicular variant of PTC (FVPTC) (n = 6), papillary microcarcinomas(n = 8), follicular thyroid carcinoma (n = 1) and the mixed form (classic PTC and FVPTC) (n = 3). The benign nodules were dominatedby: follicular adenoma (48%), and colloid goitre (40.3%).

Results: The sonographic features with predictive risk for malignancy in cases with HT associated with TND were represented by: solidcomposition, hypoechogenicity and microcalcifications. The characters of margins, the nodular shape and the type of vascularity do notseem to be as useful for identification of malignant nodules in HT. Fine needle-aspiration biopsy (FNAB) showed in DTC cases differentcytological smears: malignant (ten), indeterminate (eight), benign (two), and non-diagnostic (four). In the group of benign nodules, theindeterminate smears represented also a significant percentage (n = 12).

Conclusions: The incidence of TND associated with HT was 28.7%. Among 76 operated cases, 31.5% presented DTC. The accuracyof FNAB in the preoperative diagnosis showed higher sensitivity (90.0%) and specificity (61.5%) compared to sonographic criteria.