Hyalinizing trabecular tumor of the thyroid gland and its significant diagnostic issue

Dustin J. Jones, Christopher R. Kieliszak, Sanjay S. Patel, Christopher R. Selinsky

Hyalinizing trabecular tumors (HTT) are rare follicular cell-derived tumors of the thyroid gland that are infrequently reported in otolaryngology literature. We present here an interesting case of HTT which provides the basis for review of this entity's clinical characteristics, criteria useful in making the diagnosis, and any currently available therapeutic modalities. A 70-year-old Caucasian female underwent a CT scan of her chest and was incidentally found to have a nodule within the right thyroid lobe. Gross examination of the excised thyroid lobe revealed a circumscribed and encapsulated lesion (tan / gritty in texture), confined to the gland. Histologic sections of the lesion revealed a circumscribed neoplasm with a trabecular and organoid architecture associated with abundant dystrophic calcification. Neoplastic cells showed a spindled morphology with clumped chromatin and ample eosinophilic cytoplasm. Histologically, HTT is a follicular cell-derived tumor composed of neoplastic cells arranged in a trabecular pattern with hyalinization and calcification of extracellular material. Distinguishing features of HTT include minimal cytologic atypia with a low nuclear: cytoplasmic ratio, cellular aggregates around hyalinized material, and nuclei with clumped chromatin and occasional grooves and/or pseudoinclusions. Though debated in the literature, the general consensus is that this tumor is a benign entity. It is our hope that additional clinical research will elicit awareness of these rare tumors.