Oncocytic (Hürthle Cell) Thyroid Carcinoma

Oncocytic carcinoma, previously known as Hürthle cell carcinoma, is a rare type of thyroid cancer originating from oncocytic cells, a specialized type of follicular thyroid cell. These cells are identified by their eosinophilic cytoplasm and an abundance of granular cytoplasm. Until 2022, oncocytic carcinoma was considered a variant of follicular thyroid carcinoma, but it has since been reclassified as a separate subtype by the World Health Organization (WHO). Oncocytic thyroid carcinoma's distinct histopathological features and molecular differences, particularly mutations in the mitochondrial genome and gene expression profiles, set it apart from follicular thyroid carcinoma. Similar to other types of thyroid cancer, oncocytic carcinoma often occurs in middle-aged women as a thyroid nodule, which may not cause symptoms. Diagnosis is typically made through thyroid ultrasonography and fine-needle aspiration or core needle biopsy of the nodule. Staging oncocytic carcinoma through imaging studies may be necessary due to its increased tendency for metastatic disease. The treatment for localized oncocytic carcinoma is thyroidectomy. Unlike other types of thyroid cancer, oncocytic carcinoma has a lower tendency for radioactive iodine uptake, so this is often not a treatment option. However, newer treatments, such as tyrosine kinase inhibitors, may be considered. Treatment options continue to evolve as our knowledge of molecular markers grows, and more targeted agents become available. Due to the rarity and unique characteristics of oncocytic thyroid carcinoma, an extensive understanding of its pathophysiology, epidemiology, and optimal management strategies is essential to improving patient outcomes and guiding effective therapeutic interventions.