Frequency of Thyroid Microcarcinoma in Patients Who Underwent Total Thyroidectomy with Benign Indication-A 5-Year Retrospective Review.

Background and Objectives: Incidental thyroid cancers (ITCs) are often microcarcinomas. The most frequent histologic type is a papillary microcarcinoma. Papillary thyroid microcarcinomas are defined as papillary thyroid tumours measuring less than 10 mm at their greatest diameter. They are clinically occult and frequently diagnosed incidentally in histopathology reports after a thyroidectomy. The aim of this study is to evaluate the rate of papillary thyroid microcarcinomas (PTMC) in patients who were thyroidectomised with indications of benign disease. Materials and Methods: We retrospectively evaluated the histological incidence of PTMC in 431 consecutive patients who, in a 5 year period, underwent a thyroidectomy with benign indications. Patients with benign histology and with known or suspected malignancy were excluded. Results: Histopathology reports from 540 patients who underwent a total thyroidectomy in our department between 2016 and 2021 were reviewed. A total of 431 patients were thyroidectomised for presumed benign thyroid disease. A total of 395 patients had confirmed benign thyroid disease in the final histopathology, while 36 patients had incidental malignant lesions (33 PTMC-7.67%, one multifocal PTC without microcarcinomas-0.23%, two follicular thyroid carcinoma-0.46%). Out of the PTMC patients, 29 were female and four were male (7.2:1 female-male ratio). The mean age was 54.2 years old. A total of 24 out of 33 patients had multifocal lesions, 11 of which co-existed with macro PTC. Nine patients had unifocal lesions. A total of 21 of these patients were initially operated on for multinodular goitre (64%), while 13 were operated on for Hashimoto/Lymphocytic thyroiditis (36%). Conclusions: PTMC-often multifocal-is not an uncommon, incidental finding after thyroidectomy for benign thyroid lesions (7.67% in our series) and often co-exists with other incidental malignant lesions (8.35% in our series). The possibility of an underlying papillary microcarcinoma should be taken into account in the management of patients with benign-especially nodular-thyroid disease, and total thyroidectomy should be considered.