Thyroid Hyalinizing Trabecular Tumor: A Case Series

Aim: Hyalinizing Trabecular Tumor (HTT) of the thyroid gland is an unusual and rare follicular derived neoplasm, which was first described from Carney and colleagues in 1987. We aim to present two cases of HTT diagnosed as papillary thyroid carcinomas in preoperative FNA cytological findings, although the postoperative histological examinations revealed the presence of Hyalinizing Trabecular tumors. Moreover, a short review regarding the diagnostic and clinical aspects of this rare thyroid tumor is also presented.

Cases Presentation: A 30 year old and a 33 year old females were referred as having papillary thyroid carcinomas on preoperative FNA. Total thyroidectomy was offered in both. Histologic sections revealed the presence of HTT with the characteristic trabecular arrangement of polygonal/spindle cells and positive staining for MIB-1. Both patients remain disease free at a follow up of 5 years.

Discussion: Although HTT diagnosis and differentiation from other thyroid tumors remains a topic of controversy, immunochemistry and molecular analysis may provide adequate information for HTT distinction from papillary thyroid carcinoma (PTC), medullary thyroid cancer (MTC) and paragaglioma. Therefore, suspicious cases based on preoperative FNA, require careful evaluation and cooperation of pathologists, endocrinologists and endocrine surgeons for optimal diagnosis and treatment.

Conclusions: HTT is a rare, mostly benign neoplasm with favorable prognosis Preoperative identification of HTT is significant since its extremely low malignant potential and its favorable prognosis may lead to less extended operations and avoidance of postoperative radioiodine administration.