title: Ectopic cervical thymus: a clinicopathological study of consecutive, unselected infant autopsies.
abstract: OBJECTIVE
  An ectopic cervical thymus (ECT) is regarded as a rare congenital anomaly; therefore, the optimal diagnostic and therapeutic strategy remains a debatable matter. We designed a study to elucidate the clinicopathological characteristics of ECTs in consecutive, unselected infant autopsies, to help guide case management.
  
  
  METHODS
  We searched for ECTs in all of the 21 consecutive, unselected infant autopsy cases performed at our institution over a period of 3 years, and all ECT consensus diagnoses were confirmed by histological examination. The following clinical characteristics were evaluated in cases with ECTs: age, gender, birth week and weight, clinical symptoms due to the ECT(s), position on discovery of death, cause of death, ECT contribution to the cause of death, and concomitant congenital disorders. The anatomical features evaluated included the location, number, size, color, shape, and margins of the ECTs, and the presence of a mediastinal thymus. Histological findings of the ECT(s) and the mediastinal thymus were compared within each individual. Fusion of the parathyroid and the ECT was also investigated histologically. Spearman's rank correlation coefficient (ρ) and the corresponding P value were calculated to determine if there was an association between ECT diameter and age.
  
  
  RESULTS
  We detected 10 ECT lesions in seven cases (33%) among the 21 infant autopsy cases. The ECT cases involved five boys and two girls, with ages ranging from 1 day to 4 months. There were no reports of a positive family history of sudden death or antemortem clinical symptoms due to ECT in any of the cases. The ECTs were considered incidental regarding the cause of death, with the exception of one case that was extremely rare. Most ECTs were localized to the inferior thyroid, ranging from 0.4 to 1.9 cm in size. Size demonstrated a significant negative correlation with age (ρ=-0.75 and P=0.034).
  
  
  CONCLUSIONS
  This study revealed that ECT is an essentially benign anomaly that occurs frequently during the development of the thymus, and may disappear over the first few years of life. These results suggest a conservative approach to the management of ECTs would be appropriate.
authors.affiliation: Department of Forensic Medicine, Kyoto University Graduate School of Medicine, Yoshida-Konoe-cho, Sakyo-ku, Kyoto 606-8501, Japan. Electronic address: kotani@fp.med.kyoto-u.ac.jp.
authors.forename: Hirokazu
authors.initials: H
authors.lastname: Kotani
authors.affiliation: Department of Forensic Medicine, Kyoto University Graduate School of Medicine, Yoshida-Konoe-cho, Sakyo-ku, Kyoto 606-8501, Japan.
authors.forename: Tokiko
authors.initials: T
authors.lastname: Ishida
authors.affiliation: Department of Forensic Medicine, Kyoto University Graduate School of Medicine, Yoshida-Konoe-cho, Sakyo-ku, Kyoto 606-8501, Japan.
authors.forename: Masashi
authors.initials: M
authors.lastname: Miyao
authors.affiliation: Department of Forensic Medicine, Kyoto University Graduate School of Medicine, Yoshida-Konoe-cho, Sakyo-ku, Kyoto 606-8501, Japan.
authors.forename: Sho
authors.initials: S
authors.lastname: Manabe
authors.affiliation: Department of Forensic Medicine, Kyoto University Graduate School of Medicine, Yoshida-Konoe-cho, Sakyo-ku, Kyoto 606-8501, Japan.
authors.forename: Chihiro
authors.initials: C
authors.lastname: Kawai
authors.affiliation: Department of Forensic Medicine, Kyoto University Graduate School of Medicine, Yoshida-Konoe-cho, Sakyo-ku, Kyoto 606-8501, Japan.
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Abiru
authors.affiliation: Department of Pediatrics, Japanese Red Cross Kyoto Daini Hospital, Haruobi-cho 355-5, Kamigyo-ku, Kyoto 602-8026, Japan.
authors.forename: Tadaki
authors.initials: T
authors.lastname: Omae
authors.affiliation: Department of Pediatrics, Japanese Red Cross Kyoto Daini Hospital, Haruobi-cho 355-5, Kamigyo-ku, Kyoto 602-8026, Japan.
authors.forename: Toshio
authors.initials: T
authors.lastname: Osamura
authors.affiliation: Department of Forensic Medicine, Kyoto University Graduate School of Medicine, Yoshida-Konoe-cho, Sakyo-ku, Kyoto 606-8501, Japan.
authors.forename: Keiji
authors.initials: K
authors.lastname: Tamaki
mesh_terms: D001237:Asphyxia / Q000209:etiology; D002828:Choristoma / Q000473:pathology*; D005260:Female; D006801:Humans; D033162:Incidental Findings; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D035583:Rare Diseases / Q000473:pathology; D013950:Thymus Gland; D014133:Tracheal Diseases / Q000473:pathology*
keywords: Clinical course; Congenital anomaly; Ectopic cervical thymus; Infant; Natural incidence; Sudden unexpected death in infancy