Hyalinizing Trabecular Tumor of the Thyroid Gland: A Diagnostic and Surgical Challenge.

Hyalinizing trabecular tumors (HTTs) of the thyroid are rare benign neoplasms that often mimic papillary thyroid carcinoma (PTC) and medullary thyroid carcinoma (MTC) on cytology, creating significant diagnostic challenges. We present a case of a 38-year-old female with a 4.2 cm right thyroid nodule. Fine-needle aspiration biopsy revealed overlapping nuclei, grooves, pseudoinclusions, and stromal hyaline material, which are suspicious features of malignancy (Bethesda category V). The patient underwent total thyroidectomy. Histology showed a well-encapsulated trabecular neoplasm with extensive stromal hyalinization. Immunohistochemistry was thyroglobulin and thyroid transcription factor-1 positive, and calcitonin, chromogranin A, and carcinoembryonic antigen negative, confirming HTT. Despite these tumors being, for the most part, benign, their cytological overlap with PTC and MTC usually results in misdiagnosis and overtreatment, including unnecessary total thyroidectomy. The lack of uniform cytological or molecular markers also renders preoperative diagnosis more challenging. The current case outlines the diagnostic dilemma of HTTs and the need for improved diagnostic tools to guide appropriate management and prevent overtreatment of this otherwise benign tumor.