Multifocal papillary thyroid microcarcinoma in the end stage of Hashimoto’s thyroiditis

Introduction Frequent coexistence of papillary thyroid carcinoma (PTC) and Hashimoto's thyroiditis (HT) indicates their immunological connection, with no consensus on the cause and effect of this relationship. The aim of this report is to present an unusual case of occurrence of multifocal papillary thyroid microcarcinoma in severe thyroid atrophy as a result of the end stage of HT and to analyze its clinical significance. Case outline A 59-year-old female patient with a 14-year-long history of HT was admitted for the surgical treatment of a cytologically suspected PTC. During disease evolution, ultrasound controls were performed once a year and the findings showed a progressive decrease in thyroid volume. The nodule in the right lobe was detected for the first time in 2014. After a one-year follow-up, the nodule size was 7 mm. Fine needle aspiration biopsy was performed and was reported as "suspicious for PTC."The patient underwent total thyroidectomy. lntraoperatively, thyroid gland was indistinguishable from the surrounding tissue and histopathological intraoperative consultation was performed in order to confirm malignancy and thyroid tissue. After gross examination, all surgical specimens weighed less than 3 g. A final diagnosis of multifocal papillary thyroid microcarcinoma with bilateral presentation and extrathyroidal extension was made. Seventeen months after total thyroidectomy was performed, the patient was well, with no evidence of metastasis or recurrence of papillary carcinoma. Conclusion In the circumstances of severe thyroid atrophy, papillary microcarcinoma with infiltrative growth can lead to early extrathyroid extension, and even to the infiltration of surrounding structures.