Clinical Considerations of Oncocytic Thyroid Cancer: A Review

The fifth edition of the World Health Organization (WHO) histological classification of thyroid neoplasms released in 2022 includes newly recognized tumor types, subtypes, and a grading system.The term "oncocytic thyroid carcinoma" (OTC) is used in the new WHO classification to refer to invasive malignant follicular cell neoplasms composed of at least 75% oncocytic cells in which the nuclear features of papillary thyroid carcinoma and highgrade features are absent.As there are no reliable preoperative or intraoperative markers to identify OTC, diagnostic surgery is indicated when OTC is suspected.As the diagnosis of OTC is made postoperatively, the histopathological diagnosis frequently raises the question of completion surgery.The National Comprehensive Cancer Network (NCCN) guidelines only recommend the completion of thyroidectomy for invasive cancer (widely invasive or encapsulated angioinvasion with ≥4 vessels).In other cases, such as the encapsulated angioinvasive type with <4 vessels or minimally invasive oncocytic carcinoma, disease monitoring is preferred.Given the low rate of lymph node metastases, the benefit of routine prophylactic central lymph node dissection remains unclear, especially in the absence of vascular invasion from the primary tumor.Data regarding treatment efficacy for metastatic OTC are limited.However, trials with systemic therapy with targeted kinase inhibitor therapy support the use of sorafenib and lenvatinib.