Abstract
We report an extremely rare case of solitary thyroid metastasis from the rectum. A 65-year-old woman undergoing low anterior resection for rectal adenocarcinoma was given a definitive pathological diagnosis of moderately differentiated adenocarcinoma, pT2 (ss), pN1, stageIIIa. Postoperatively, she underwent adjuvant chemotherapy 5 cycles with UFT/UZEL. Ten months later, computed tomography (CT) showed a low-density left thyroid gland nodule with swollen cervical lymph nodes. Fine-needle aspiration biopsy of the nodule showed carcinoma cells, necessitating thyroidectomy and modified neck dissection based on a diagnosis of primary thyroid carcinoma. Histological examination showed that the thyroid adenocarcinoma had metastasized from the rectum. No involvement of regional lymph nodes was seen. Postoperative physical and imaging examinations found no evidence of metastasis. Although metastasis to thyroid gland is recognized in autopsy studies, tumor metastasis localized in the thyroid gland is clinically uncommon.
