Endocrine Abstracts

Introduction: Hyalinizing trabecular adenomas (HTA) of the thyroid gland is a rare neoplasm of follicular cell origin. HTA can be present as a thyroid nodule or incidental finding in a thyroidectomy specimen. HTA is generally accepted to be a benign tumor, but their cytological features can be similar to those of papillary thyroid carcinoma (PTC).

Case report: A 59 year old woman, who had cholangiocellular carcinoma, admitted to our institution with a solitary thyroid nodule and cervical lymphadenopathy. Fine needle aspiration biopsy of the cervical lymphadenopathy revealed suspicious for carcinoma metastasis. Her serum free thyroxine (fT₄), free triiodothyronine (fT₃) and TSH levels are 1.42 ng/dl, 2.82 pg/ml, and 0.486 mIU/ml. Ultrasonography of the thyroid gland showed a 1.4 cm sized, regularly marginated, hypoechoic, calcified thyroid nodule. Fine needle aspiration biopsy of the thyroid nodule revealed suspicious for PTC. Total thyroidectomy were perfomed. The final pathology was 1.0-cm sized hyalinizing trabecular adenoma. Histologically, the tumor showed tumor cells arranged in trabeculae and a prominent hyaline stroma. The neoplastic cells were focally immunoreactive for thyroglobulin and negative for calcitonin and chromogranin. After surgery L-thyroxine replacement therapy was started. Cervical metastasis was thought to be associated with cholangiocellular carcinoma. The patient referred to the Oncology department for the treatment of metastatic cholangiocellular carcinoma.

Conclusion: Ultrasonografic features of HTA similar to malign thyroid lesions and frequently misdiagnosed as papillary carcinoma on fine-niddle aspiration cytology. The most recent and controversial debate surrounding HTA concerns its potentially malignant behavior and the possible relationship to PTC. Although cases of malignant HTA have been recorded, HTA should be considered a benign neoplasm or, at most, a neoplasm of extremely low malignant potential. In this report we present and discuss an unusual case of a patient who had a hyalinizing trabecular adenoma and cholangiocellular carcinoma.