Incidental thyroid carcinoma diagnosed after total thyroidectomy for benign thyroid diseases: incidence and association with thyroid disease type and laboratory markers.

Objective. Currently, total thyroidectomy (TT) is widely used to treat benign thyroid diseases and thyroid carcinoma. The differential diagnosis between benign and malignant thyroid disorders and the potential identification of thyroid microcarcinomas with biochemical markers remain controversial. This retrospective study aimed to estimate the prognostic validity of thyroid autoantibodies, thyroglobulin (Tg), and the thyroid disease type in diagnostic approaches regarding the co-existence of incidental thyroid carcinoma (ITC) with benign thyroid diseases. Methods. A cohort of 228 patients was treated with TT for benign thyroid disorders between 2005 and 2010. Thyroid autoantibodies and Tg were preoperatively estimated. Patients were classified according to the preoperative and histologically established diagnoses, and the median values of the biochemical markers were compared between the groups. Results. ITC was detected in 33/228 patients and almost exclusively in the presence of nontoxic thyroid disorders (P = 0.014). There were no statistically significant differences in the median values of the biochemical markers between the benign and malignant groups. There was also no significant association between ITC and chronic lymphocytic thyroiditis. Conclusions. The co-existence of ITC with benign and especially nontoxic thyroid diseases is significant, and treatment of these disorders with TT when indicated can lead to the identification and definitive cure of microcarcinomas. Further studies are required to establish precise markers with prognostic validity for TC diagnosis.