title: Immature teratoma of the mediastinum arising in ectopic thyroid tissue: a case report.
abstract: BACKGROUND
  Papillary carcinoma can arise from ectopic thyroid tissue, but teratoma have not been described. Differentiation into thyroid follicles does not occur in mediastinal teratomas.
  
  
  METHODS
  A case of upper mediastinal immature teratoma occurred in an 18-day-old male newborn. The histologic examination revealed the presence of a discontinuous rim of compressed thyroid follicles on the outer aspect of the tumor capsule. This finding is consistent with the origin of the teratoma in ectopic thyroid tissue, and it has not been previously described in the literature. The patient was free of disease after 22 months, in accordance with the benign behavior of immature teratoma in infancy.
  
  
  CONCLUSIONS
  Ectopic thyroid tissue can undergo the same pathologic changes as the thyroid gland, including the rare occurrence of teratoma.
authors.affiliation: Department of Pathology, Ospedali Riuniti di Ancona, Ancona, Italy. r.ranaldi@ospedaliriuniti.marche.it
authors.forename: Renzo
authors.initials: R
authors.lastname: Ranaldi
authors.forename: Doriana
authors.initials: D
authors.lastname: Morichetti
authors.forename: Gaia
authors.initials: G
authors.lastname: Goteri
authors.forename: Ascanio
authors.initials: A
authors.lastname: Martino
mesh_terms: D002828:Choristoma / Q000150:complications / Q000378:metabolism / Q000473:pathology* / Q000601:surgery; D004417:Dyspnea / Q000209:etiology; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D008479:Mediastinal Neoplasms / Q000150:complications / Q000378:metabolism / Q000473:pathology* / Q000601:surgery; D008482:Mediastinum / Q000473:pathology / Q000601:surgery; D009687:Nuclear Proteins / Q000378:metabolism; D013724:Teratoma / Q000150:complications / Q000378:metabolism / Q000473:pathology* / Q000601:surgery; D013954:Thyroglobulin / Q000378:metabolism; D013961:Thyroid Gland / Q000473:pathology*; D000074482:Thyroid Nuclear Factor 1; D014132:Trachea / Q000473:pathology; D014157:Transcription Factors / Q000378:metabolism
chemical_list: D009687:Nuclear Proteins; D000074482:Thyroid Nuclear Factor 1; D014157:Transcription Factors; D013954:Thyroglobulin