Endocrine Abstracts

Introduction: Hyalinizing trabecular tumors are extremely rare and uncommon thyroid tumors, which were first described by Carney et al. Until now, their preoperative diagnosis based on cytological characteristics is not possible, because of the lack of specific features and molecular markers.

Case presentation: We present a 38-year-old Caucasian female, non-smoker, with a disease-free medical history, with a right-sided clearly delimited large hypoechoic thyroid lesion measuring 4.2 cm in its greatest dimension as detected by neck sonography. The patient underwent a FNAB, which showed overlapping elongated nuclei, nuclear grooves, pseudoinclusions and stromatic hyaline material between the cell clusters. The lesion was characterized as suspicious for malignancy (Bethesda Category V). A total thyroidectomy was performed. Histologic examination confirmed a 4.2 cm encapsulated nodule on the right side of the thyroid gland. The tumor cells were polygonal to elongated with eosinophilic cytoplasm and arranged in an alveolar or trabecular pattern, while extensive hyaline material was presented at the stroma. Their nuclei exhibited nuclear grooves and pseudoinclusions. Immunohistochemical staining showed positivity for thyroid transcription factor-1, thyroglobulin and negativity for chromogranin A, calcitonin, carcinoembryonic antigen, cytokeratin 19, HBME-1. These findings were compatible with thyroid hyalinizing trabecular tumor. Treatment of hyalinizing trabecular tumors remains conservative. Patient’s follow-up after thyroidectomy remains the same as the one followed after surgical removal of a thyroid neoplasm with low malignant potential.

Conclusion: Novel cytologic features including molecular panels unique for hyalinizing trabecular tumor would be of great value for pre-surgery recognition and prevention of overtreatment with thyroidectomy for treating an almost benign disease.