Localization of cervical lymphadenopathy due to colorectal adenocarcinoma metastasis to the thyroid with intraoperative ultrasound Localización con ecografía intraoperatoria de adenopatías cervicales secundarias a metástasis tiroidea de adenocarcinoma de colon

We report the case of a 51-year-old female patient who had undergone sigmoidectomy for adenocarcinoma (T3 N1 M0) and adjuvant chemotherapy (CT) and had metastatic disease five years after the initial diagnosis. Computed tomography (CT) showed metastases in the right thyroid lobe (RTL), the tail of the pancreas, and the left lower lobe of the lung, which were confirmed by positron emission tomography (PET). The patient was euthyroid, and the physical examination was normal. Neck ultrasound examination showed a hypoechoic, calcified nodule in the RTL. Fine needle aspiration (FNA) suggested papillary thyroid carcinoma versus metastases from colon adenocarcinoma. CT was administered, and imaging tests after three years of follow-up showed a reduction in the pulmonary lesion and the disappearance of the pancreatic lesion. The thyroid nodule remained stable, however, and suspicious adenopathies were found in the right carotid-jugular region in a control ultrasound examination. After an evaluation of the case at a multidisciplinary session, both total thyroidectomy and central and right lateral lymphadenectomy were performed. A radiologist who specialized in the thyroid gland performed an intraoperative ultrasound examination before incision to confirm the localization of the suspicious adenopathies. Repeat ultrasound examination after lymphadenectomy showed a persistent suspicious adenopathy in a higher localization of level II, which had been overlooked and this was excised. The histological examination was consistent with a thyroid metastasis from colon adenocarcinoma, with two positive lymph nodes out of the 25 excised, one of them being the one located by intraoperative ultrasound examination. The patient recovered uneventfully and, after one year of follow-up, she is currently receiving adjuvant therapy and there has been no evidence of thyroid recurrence. Metastases account for only 1.4--3% of all thyroid malignancies.1--3 They should however be considered in any differential diagnosis of patients with a thyroid lesion and a history of cancer at another location. Some authors state that the number of cases of metastatic disease in the thyroid gland has increased in recent years.4 The primary tumors most commonly metastasizing to the thyroid gland are the renal cell (48.1%), colorectal (10.4%), lung (8.3%), and breast tumors (7.8%).5 Other less commonly associated tumors include sarcoma,