What is Hürthle Cell Carcinoma?
Hürthle cell carcinoma (HCC) is a rare type of
thyroid cancer originating from Hürthle cells, also known as oxyphilic cells. These cells are characterized by their abundant eosinophilic cytoplasm, which is due to the high content of
mitochondria. HCC is often considered a variant of follicular thyroid carcinoma but has distinct histological and clinical features.
Histological Features
Under the microscope, Hürthle cells appear as large, polygonal cells with granular, eosinophilic cytoplasm. The nucleus is typically round and may contain prominent nucleoli. The cytoplasm's granular appearance is due to the large number of mitochondria. In HCC, these cells invade the thyroid capsule and blood vessels, distinguishing it from benign Hürthle cell adenomas.Diagnosis
Diagnosing HCC involves a combination of imaging studies, fine-needle aspiration (FNA) cytology, and histopathological examination. During FNA, the presence of abundant Hürthle cells raises suspicion but is not definitive for malignancy. A definitive diagnosis is usually made post-operatively through histological examination, where capsular and/or vascular invasion by Hürthle cells is identified.Clinical Presentation
Patients with HCC often present with a painless, rapidly enlarging thyroid nodule. Some may experience symptoms related to compression of adjacent structures, such as difficulty swallowing or breathing. Unlike other thyroid cancers, HCC rarely presents with
hyperthyroidism or
hypothyroidism.
Treatment
The primary treatment for HCC is surgical removal of the affected thyroid tissue, typically through a total thyroidectomy. Due to the risk of recurrence and metastasis, radioactive iodine therapy may be considered, although Hürthle cells are often less responsive to this treatment compared to other thyroid cancers. Post-surgery, patients are monitored with periodic imaging and
thyroglobulin levels to detect any recurrence.
Prognosis
The prognosis for HCC varies depending on factors such as the extent of invasion, size of the tumor, and presence of metastasis. Generally, HCC has a worse prognosis compared to other differentiated thyroid cancers, primarily due to its higher recurrence rates and potential for distant metastasis. Early detection and comprehensive treatment are crucial for improving outcomes.Research and Future Directions
Ongoing research aims to better understand the molecular and genetic underpinnings of HCC. Studies are exploring the role of mutations in genes such as
TP53 and
NRAS in the pathogenesis of HCC. Advances in molecular diagnostics and targeted therapies hold promise for more effective management of this challenging thyroid cancer variant.
