Incidental thyroid papillary microcarcinoma on 1777 surgically treated patients for benign thyroid disease: A monoinstitutional experience and literature review

Background: We evaluated the frequency of incidental papillary thyroid microcarcinomas (mPTC) in thyroidectomies performed for benign diseases, to better characterize this nosologic entity and to assess the best treatment. Methods: Between 2009 and 2017, a total of 1777 patients underwent surgery for benign thyroid disease. Patients with preoperative undetermined or positive for malignancy cytology were excluded, as well as incidental thyroid cancer larger than 1 cm. Results: Total thyroidectomy was performed in 1649 patients (92.7%) and hemithyroidectomy in 128 (7.2%). Papillary thyroid cancer, sized between 2–10 mm, was found in 89 patients (5%), which were all by definition microcarcinomas (mPTC). In 11 patients mPTCs were multifocal and in 7 bilateral. Just 6 patients received hemithyroidectomy and later underwent radical surgery without complications. No tumor-related morbidity or mortality was observed. The χ2 test showed a statistically significant association between mPTC and non-toxic multinodular goiter. Discussion: In the literature, the rates of incidental mPTC vary, due to various factors such as histopathological examination and sampling numbers. Regarding surgical treatment, some authors support a “conservative” approach for the positive prognosis, but considering that it can be associated with mortality, lymph node recurrence and metastasis, its treatment is still controversial. Conclusions: Our experience confirms that total thyroidectomy in multinodular goiter is a safe procedure, which ensures endocrine control and oncologic complete tumor resection, in case of mPTC. In uninodular goiter, we recommend hemithyroidectomy; if mPTC is discovered, we suggest radical surgery especially in patients older than 50 years and with familial disposition for thyroid cancer and peripheral tumors larger than 5 mm and aggressive variants.