Mehri Kalhor - PhD student of Reproductive health of Tarbiat Modarres University, Kowsar Hospital of Qazvin University of Medical Sciences
Fatemeh Samii rad - Pathologist, Associate Professor, faculty of Medicine University of Qazvin University of Medical Sciences
Mohamad reza Maleki - Assistant Professor of Pediatrics School of Medicine Qazvin university of medical sciences
Amir Farzam - Assistant professor of pathology, Qazvin University of Medical Scienes.Qazvin, Iran

Background: Hyalinizing trabecular adenoma (HTA) is an exceptional neoplasm arising from follicular cells. Hyalinizing trabecular adenoma can imitate another thyroid gland malignancies mainly composed of papillary and medullary carcinomas, in cytopathlogy and histopathology. Also neoplastic follicular cells in this tumor have RET/PTC rearrangements. Therefore clinical behavior of HTA cannot benign. Here, we present a case of a hyalinizing trabecular adenoma with literature review.Case presentation: A 60-year-old man presented at our hospital with neck mass. Physical examination showed a mobile, non-tender, thyroid nodule.Thyroid function tests were normal limit. Radiological examination including Ultrasonography studies revealed hypoechoic nodule with well-defined borders, M: 10*8*6 cm in right lobe. Fine needle aspiration cytology was reported as suspicious for papillary carcinoma. Frozen Sections examination diagnosis was Hurthle cell neoplasm. Permanent histopathological diagnosis was hyalinizing trabecular adenoma. The patient was disease free in the following 14 months. Conclusion: Although, thyroid gland hyalinizing trabecular adenoma is a rare form of follicular neoplasm in routine clinical practice, there are doubtful cytopathologic and cytogenetic findings in favor of non-benign biologic behavior. Therefore, it is necessary for the surgeon to be aware of lesion. Also the pathologists should be differentiate between THA with papillary or medullary carcinoma.

Hyalinizing trabecular adenoma, Thyroid gland