A Case of Hyalinizing Trabecular Adenoma of the Thyroid Gland

Hyalinizing trabecular tumor is a rare benign thyroid tumor first described by Carney et al. in 1987. The tumor is characterized by an encapsulated nodule, trabecular arrangement of polygonal, oval, elongated cells, and hyalinized stroma. It is easily confused with papillary thyroid carcinoma or medullary thyroid carcinoma on surgical and cytologic specimens. A 45-year-old man presented with an incidentally detected left thyroid mass. Fine needle aspiration was performed and papillary thyroid carcinoma was suspected. However, the surgical specimen revealed a hyalinizing trabecular adenoma. We present this hyalinizing trabecular adenoma case to share our experience with physicians and specialists. (J Korean Endocr Soc 24:54~57, 2009)