Hyalinizing trabecular tumor is an uncommon, controversial lesion of thyroid gland. Hyalinizing trabecular neoplasm share similarities with medullary thyroid carcinomas (MTC) and exhibit nuclear features resembling papillary thyroid carcinoma (PTC). However, the clinical behaviour unclear. We aimed to present a rare case of hyalinizing trabecular tumor of thyroid gland and ten-year follow up. A 54-year-old woman who was being followed up because of multinodular goiter on examination of neck, the thyroid gland was nodular, measured 20 mm×10 mm and non-tender. Serum FT3, FT4 and TSH were within normal limits. Ultrasonography showed a hypoechoic nodular lesion of 12 mm×6 mm in the right lobe and 29 mm×11 mm hypoechoic nodular lesion in the left lobe. Fine needle aspiration cytology the diagnosis was suspicious due to cells similar to papillary carcinoma cells. She underwent a total thyroidectomy. Histopathological examination showed the nuclei were oval, slightly pleomorphic, trabecular growth pattern, intratrabecular hyalinization and nuclei with grooves and cytoplasmic pseudoinclusions. Immunohistochemically the tumor was thyroglobulin positive, and calcitonin and HBME-1 negative, galectin 3 and TTF-1 focal positive.The pathological diagnosis was hyalinizing trabecular tumor with lympositic thyroiditis. L-thyroxine 0.1 mg/day therapy was started. The patients treated was found to be euthyroid over the ten year follow-up period. Hyalinizing trabecular tumor is a unique neoplasm of follicular derivation. Most authors consider this tumor to be benign. The differentiation of hyalinizing trabecular tumor from other thyroid tumors such as PTC and MTC, based on overlapping nuclear features. Cytological diagnosis of hyalinizing trabecular tumor has a characteristic trabecular growth pattern and hyalinizing stroma. The prognosis of hyalinizing trabecular tumor is favorable.
20 - 23 May 2017
European Society of Endocrinology