A Case of Hyalinizing Trabecular Adenoma of the Thyroid

We report a case of trabecular adenoma of the thyroid. A 68-year-old woman complained of front neck swelling in November 2007 and neck echo demonstrated a mass in thyroid. The mass was diagnosed as papillary carcinoma based on fine needle aspiration performed in Ogori Daiichi General Hospital. Therefore, the tumor was surgically resected at our hospital. After surgery, the tumor was diagnosed as hyalinizing trabecular adenoma on histological examination. The cytology of hyalinizing trabecular adenoma resembles those of papillary carcinoma and medullary carcinoma, although the former tumor is categorized in the benign tumors. Therefore, the tumor is often misdiagnosed as papillary carcinoma or medullary carcinoma. Hyalinizing trabecular adenoma is very rare.