title: Saccular aortic aneurysm that resembled a mediastinal neoplasm.
abstract: BACKGROUND
  Saccular aortic arch aneurysms in unusual sites may be misdiagnosed as a neoplasm. We present the case of a rare saccular aortic arch aneurysm between trachea and esophagus that resembled a mediastinal neoplasm in the preoperative findings.
  
  
  METHODS
  A 63-year-old male with an abnormal mediastinal shadow on chest X-ray was referred to the hospital. An axial plain computed tomogram of the chest revealed mediastinal soft tissue next to the right side of the aortic arch resembling a neoplasm originating from the gap between the trachea and the esophagus. The coronal view constructed by enhanced 64-row multi detector computed tomography revealed the soft tissue was an aneurysm arising from the inner side of the aortic arch. An aortic arch replacement was performed via a median sternotomy.
  
  
  CONCLUSIONS
  A thoracic aortic aneurysm sometimes behaves like a mediastinal neoplasm. The multiple cross-sectional image from multidetector computed tomography was useful for the correct diagnosis of such an aneurysm.
  
  
  CONCLUSIONS
  The possibility of an aneurysm should be considered whenever a mass in contact with the aortic wall is identified.
authors.affiliation: Department of Thoracic Surgery, Shinyukuhashi Hospital, 1411 Ooazadoujyouji, Yukuhashi 824-0026, Japan. Electronic address: nose@shinyukuhashihospital.or.jp.
authors.forename: Naohiro
authors.initials: N
authors.lastname: Nose
authors.forename: Hiroumi
authors.initials: H
authors.lastname: Kataoka
authors.forename: Masakatsu
authors.initials: M
authors.lastname: Hamada
authors.forename: Yukio
authors.initials: Y
authors.lastname: Kosako
authors.forename: Yasuji
authors.initials: Y
authors.lastname: Matsuno
authors.forename: Takahiro
authors.initials: T
authors.lastname: Ishii