Abstract
INTRODUCTION AND IMPORTANCE: Thyroid metastasis of colorectal cancer is rare and the patient with thyroid metastasis has no symptoms early in the disease course. On the other hand, evaluation of thyroid is not generally included in the routine follow-up of colorectal cancer. Therefore, the diagnosis of thyroid metastasis of colorectal cancer may be delayed. PRESENTATION OF CASE: Chest computed tomography revealed a nodule on the right lobe of the thyroid in 53-year-old woman diagnosed with sigmoid colon adenocarcinoma. This nodule was identified having as increased metabolic activity by (18)F-fluorodeoxyglucose positron emission tomography-computed tomography and confirmed to be consisted of cystic and solid portions by ultrasonography. Fine needle aspiration cytology of the nodule revealed metastasis of colon cancer. The patient underwent laparoscopic anterior resection and a total thyroidectomy. The size of the thyroid tumor was 1.2 cm with free resection margin. DISCUSSION: The clinical features of thyroid metastasis from colorectal cancer are not typical. In addition, follow-up examinations of patients with colorectal cancer do not include imaging studies of the neck, so the diagnosis of thyroid metastases is delayed. The management strategies for thyroid metastasis from colorectal cancer include a total thyroidectomy without prophylactic neck lymph node dissection and chemotherapy. However, as the penetration of chemotherapeutic drugs into the thyroid is difficult, the effect on the thyroid is considered insignificant. CONCLUSION: Surgical treatment should be considered for treatment of thyroid metastasis.