Thyroid Gland as a Metastatic Site for Hepatocellular Carcinoma: A Rare Case Report.

Background: Thyroid gland metastasis from distant primary tumors is uncommon, with liver cancer being a particularly rare source. This case report describes the clinical challenges and diagnostic journey of a thyroid mass in a patient with chronic hepatitis B, liver cirrhosis, and hepatocellular carcinoma, underscoring the rarity and complexity of such metastatic relationships.

Case presentation: A 63-year-old male with a long-standing history of hepatitis B-related liver cirrhosis and a recent diagnosis of hepatocellular carcinoma presented with a rapidly enlarging painful right-sided thyroid mass associated with swelling but no systemic symptoms such as fever or dysphonia. This prompted a thorough diagnostic workup. Enhanced neck scans indicated a mass potentially originating from the thyroid with tracheal compression, yet crucially, there was no evidence of lung involvement based on the chest CT. Despite the rarity of liver-to-thyroid metastasis, the patient's multifaceted medical history warranted a broad differential diagnosis.

Intervention and outcome: Surgical intervention included a right-sided thyroidectomy and partial left thyroidectomy under general anesthesia. Histopathological examination unexpectedly confirmed the presence of metastatic thyroid cancer originating from the primary liver tumor. This led to further extensive surgical management, including lymph node dissection in the central neck area. The postoperative regimen was adapted to include thyroid hormone replacement and ongoing treatment for hepatocellular carcinoma. The patient's postoperative recovery was closely monitored, reflecting stable disease with no immediate complications.

Conclusion: This case highlights the clinical rarity and diagnostic challenges of liver cancer metastasizing to the thyroid. It emphasizes the need for vigilance in patients with known primary malignancies, especially hepatocellular carcinoma, presenting with new thyroid abnormalities. This advocates for a comprehensive diagnostic approach in such atypical presentations.