Hyalinizing trabecular tumor of the thyroid : a clinicopathological study of ten cases

LI Jie; SONG Xin; SHI Huai-yin

doi:10.3969/j.issn.1007-8096.2018.02.006

Abstract：Objective To investigate the clinicopatholocical characteristics and diagnosis and differential diagnosis of hyalinizing trabecular tumors (HTT) of the thyroid.Methods The clinical manifestations,morphological and immunohistochemical features were analyzed in ten cases of HTT of our department.The associated literatures were discussed with the key points of the diagnosis and the differential diagnosis.Results There were 7 females and 3 males patients aged from 27 to 61 years (mean 49.9 yeas).Eight tumors located in the left lobe of the thyroid and 2 tumors in the right lobe.There were 8 specimen from thyroidectomy and 2 cases from core needle biopsy.Grossly,diameter of the tumors ranged from 6 cm to 0.2 cm.Microscopically,the tumor typically consisted of a trabecular growth pattern and hyalinizing material deposited intratrabecular widespreadlly.The cytological features mimicked papillary thyroid carcinoma (PTC).The tumor cells were polygonal,oval,or high columnar with an acidophilic or clear cytoplasm.The nuclei were oval with inconspicuous small nucleoli,prominent grooves and pseudoinclusions.Mitosis was rare.Cytoplasmic yellow bodies were frequently found.Immunohistochemically,tumor cells were positive for TTF-1 (10/10),TG (10/10),CD56 (10/10),and negativity for Syn,Calcitonin and CgA.Galectin-3 was expressed weakly in 3 cases (3/10),and 2 of 10 cases expressed CK19.Staining with the Ki-67 (MIB-1) antibody showed membranous and cytoplasm immunoreactivity of all cases (10/10),whereas an other clone of Ki-67 (SP6) showed a common nuclear pattern,with an index less than 1％.After a follow-up for 12 months to 11 years,the patients were alive without local recurrence or metastasis.Conclusions HTT is a rare thyroid tumor with no specific clinical features.But it is often misdiagnosed.The correct diagnosis of HTT mainly depends on typical histopathological features and characteristic expression pattern of MIB-1 immunohistochemical staining.HTTs are neoplams with very low malignant potential,which need long term follow-up.