Ultrasonographic characteristics of thyroid metastasis from clear cell renal cell carcinoma: A case report

INTRODUCTION: Thyroid metastasis from clear cell renal cell carcinoma (ccRCC) is a very rare condition, and its ultrasonographic characteristics have not been summarized in the literature. We herein report a case of thyroid metastasis from ccRCC that occurred 11 years after the surgery and the ultrasonographic characteristics of it are described. PATIENT CONCERNS: A 57-year-old male patient was admitted to our hospital in September 2018 due to discomfort in the neck. No other abnormalities were found during laboratory examination of thyroid function. The previous medical history of the patient included a right nephrectomy for the treatment of ccRCC in June 2007. DIAGNOSIS: Ultrasound examinations revealed multiple thyroid nodules. After nephrectomy, there was no obvious abnormality in the right renal area. Computed tomography (CT) showed an oval lesion with slightly lower density in the right lobe of the thyroid, and the patient was initially diagnosed with nodular goiter. INTERVENTIONS: Bilateral partial thyroidectomy under general anesthesia was conducted. Intraoperative frozen pathological examination showed clear cell carcinoma in the right lobe of the thyroid gland. Therefore, total thyroidectomy and lymph node dissection in the central neck area were performed. OUTCOMES: The patient underwent surgical treatment and recovered successfully. The patient was followed up for 2 years with no further metastasis. CONCLUSION: Ultrasound examination is a safe and convenient screening method. For patients with a renal malignant tumor, if the ultrasound image of thyroid nodule is found to have the characteristics of malignant tumors, the occurrence of metastasis of renal cancer to the thyroid should be highly suspected. Core needle biopsy (CNB) and histopathological diagnosis should be conducted subsequently for early diagnosis.