Hyalinizing Trabecular Tumor of the Thyroid: A Case Report

Hyalinizing trabecular tumor (HTT) of the thyroid is a rare neoplasm that was first described by Carney in 1987. It is a tumor of follicular derivation with peculiar nuclear, architectural, histochemical, and immunohistochemical features. We report a case of HTT in a 69-year-old woman with a mutinodular goiter. Since the clinical and ultrasonographic features were nonspecific, fine needle aspiration biopsy (FNAB) of the left lobe-dominant node was performed that resulted in an indeterminate cytologic diagnosis (category THY-3). The patient underwent total thyroidectomy, with a histologic diagnosis of HTT. We discuss the clinical and diagnostic approach, including the role of FNAB, and the pathologic features of HTT with special reference to the possible differential diagnosis. Total thyroidectomy or hemithyroidectomy represent adequate treatments, while radioiodine ablation is not standard. Although rare cases of malignant HTT have been documented, this tumor should be considered a benign neoplasm or, at most, a neoplasm of extremely low malignant potential. As a consequence, once this diagnosis is rendered, clinical management should be conservative, which may include a precautionary annual follow-up in order to exclude the very rare possibility of recurrence, as exceptionally reported.