Clinical features and outcomes of thyroid hyalinizing trabecular tumors: An 11-year experience at a tertiary referral hospital.

Hyalinizing trabecular tumors (HTTs) of the thyroid are rare neoplasms that generally exhibit benign behavior, lacking capsular or vascular invasion. Despite this, HTTs often present histopathological features that closely resemble those of papillary thyroid carcinoma (PTC), posing an important diagnostic challenge and leading to the frequent misinterpretation of fine needle aspiration biopsy (FNAB) results as PTC. The present study aimed to investigate the clinical characteristics and outcomes of HTTs observed over 11 years at a tertiary referral hospital [Chonnam National University Hwasun Hospital (Hwasun, South Korea)]. A retrospective analysis was conducted on 11 patients with pathologically confirmed HTT, evaluated between March 2011 and December 2021, following their final histological examinations after surgery. Of the 9,169 patients who underwent thyroid surgery during this period, 11 patients (0.12%) were histologically diagnosed with HTT. FNAB was performed in 10 patients, but HTT was included in the differential diagnosis in only 1 patient, while 6 patients were suspected as PTC or unspecific carcinoma. The average tumor size measured by preoperative ultrasonography (US) was 1.7±1.1 cm (range, 0.3-3.9 cm). The majority of tumors appeared hypoechoic with well-defined margins, and no US features indicative of malignancy were observed. Surgical management included thyroid lobectomy in 6 patients and total thyroidectomy in 5 patients. Over a mean follow-up period of 38 months, no recurrences or metastases were observed. In summary, these findings highlight the limited diagnostic utility of FNAB or US in the preoperative identification of HTTs. In cases where preoperative US findings are benign and FNAB results suggest PTC, HTT should be considered in the differential diagnosis to avoid overtreatment.