Metastatic thyroid carcinoma to the gastric body.

Abstract

A 46-year-old woman had a 4-month history of progressive cough, dysphagia, and dysphonia. Laryngoscopy revealed left vocal cord paralysis, and computed tomography demonstrated a mediastinal mass arising from the thyroid and invading the trachea and esophagus (Figure 1). A biopsy of the mass revealed papillary thyroid carcinoma (PTC). The patient underwent bilateral neck dissections and total thyroidectomy with en bloc resection of the mediastinal mass with 3 cm of trachea and outer muscular layer of the esophagus. Histological examination identified PTC with regions of poorly differentiated thyroid carcinoma (PDTC) in nodal metastases and in areas of extrathyroidal extension (pT4aN1b); margins were involved. Angioinvasion was characterized by intravascular tumor cells admixed with thrombus (1). Postsurgical thyroglobulin was undetectable ( 0.9 g/L); thyroglobulin antibodies were positive (183 IU/L). Following 200 mCi of radioactive iodine, no uptake outside the neck was identified. The patient received prophylactic external beam radiotherapy to the neck and superior mediastinum. Four months after surgery, she was found to have lung metastases with increasing thyroglobulin antibodies (551 IU/L). The low-burden lung disease remained relatively stable. Sixteen months after surgery, a postcricoid esophageal stricture was diagnosed. During gastroscopy to dilate it, a 1.5-cm suspicious nodule in the proximal body of the stomach was noted and biopsied. This was metastatic PTC with areas of PDTC. Although most thyroid carcinomas encountered in visceral organs represent metastatic disease, these can also arise within teratomas and ectopic thyroid tissues (2). Anaplastic thyroid carcinoma is known to metastasize to the stomach; however, intra-abdominal metastases from PTC or PDTC are extremely uncommon (3, 4). The application of rigid criteria to diagnose vascular invasion as identified in this case provides a clinically relevant prediction of distant metastasis in patients with thyroid carcinomas (1). To the best of our knowledge, this is the first reported gastric metastasis originating from PTC with regions of PDTC.