title: Gastroenteropancreatic neuroendocrine tumor metastases to the thyroid gland: differential diagnosis with medullary thyroid carcinoma.
abstract: Neuroendocrine tumors (NET) of the thyroid gland are rare. Apart from medullary thyroid carcinoma (MTC), metastases of gastroenteropancreatic (GEP) NET may also occur. Features of six patients (five men, one female: age range, 39-67 years) with thyroid metastases from a GEP-NET are described. Thyroid metastases were bilateral in all patients and were associated with enlarged neck lymph nodes in five. In four cases, the thyroid tumor was either the first sign of the disease (n = 2) or was an isolated site of recurrence (n = 2). The tumors were well (n = 3) or poorly differentiated (n = 3). Five tumors for which the primary site could be determined corresponded to foregut-derived tumors (3 lungs, 1 thymus and 1 pancreatic NET). One tumor demonstrated calcitonin (CT) production as shown by immunohistochemistry and elevated plasma CT levels. However, the disease history and the clinical features strongly favored a metastasizing GEP-NET. No tumoral RET proto-oncogene mutation was found in this patient. The differential diagnosis between metastatic GEP-NET and MTC is crucial because prognosis, work-up, and treatment differ greatly.
authors.affiliation: Service de Médecine Nucléaire, Institut Gustave-Roussy, Villejuif, France.
authors.forename: S
authors.initials: S
authors.lastname: Leboulleux
authors.forename: E
authors.initials: E
authors.lastname: Baudin
authors.forename: J
authors.initials: J
authors.lastname: Young
authors.forename: B
authors.initials: B
authors.lastname: Caillou
authors.forename: V
authors.initials: V
authors.lastname: Lazar
authors.forename: G
authors.initials: G
authors.lastname: Pellegriti
authors.forename: M
authors.initials: M
authors.lastname: Ducreux
authors.forename: G
authors.initials: G
authors.lastname: Schaison
authors.forename: M
authors.initials: M
authors.lastname: Schlumberger
mesh_terms: D000328:Adult; D000368:Aged; D002116:Calcitonin / Q000097:blood; D002272:Carcinoembryonic Antigen / Q000097:blood; D018276:Carcinoma, Medullary / Q000175:diagnosis; D004273:DNA, Neoplasm / Q000097:blood; D003937:Diagnosis, Differential; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008175:Lung Neoplasms / Q000473:pathology; D008297:Male; D008875:Middle Aged; D018358:Neuroendocrine Tumors / Q000473:pathology / Q000556:secondary*; D010190:Pancreatic Neoplasms / Q000473:pathology; D018807:Polymorphism, Single-Stranded Conformational; D011446:Prospective Studies; D000090063:Proto-Oncogene Mas; D013953:Thymus Neoplasms / Q000473:pathology; D013964:Thyroid Neoplasms / Q000175:diagnosis / Q000556:secondary*
chemical_list: D002272:Carcinoembryonic Antigen; D004273:DNA, Neoplasm; C000715470:MAS1 protein, human; D000090063:Proto-Oncogene Mas; D002116:Calcitonin