title: Sclerosing mediastinitis of unknown origin: Report of a case.
abstract: BACKGROUND
  We herein describe a rare case of a sclerosing mediastinitis without IgG4-related disease. This case was clearly excluded from IgG4-related disease, because this patient's serum IgG4 level was not elevated. Specifically, this patient's serum IgG4 level was 7.9mg/dl (4.8-105).
  
  
  METHODS
  A 61-year-old Japanese female presented at our hospital due to an abnormal chest X-ray that showed a growing shadow in the mediastinum. Chest computed tomography (CT) showed an 80×75×75mm tumor, which located in the anterior mediastinum. This large tumor surrounded the thoracic aorta, left brachiocephalic vein and superior vena cava. It was difficult to obtain a definitive diagnosis. We tried to perform three biopsies, and eventually performed a partial resection of the tumor.
  
  
  CONCLUSIONS
  This case did not fit the criteria for IgG4-related disease, and it was therefore unclear whether steroid therapy should be used for this case. We will continue to carefully follow up this patient's residual lesion, and there have been no changes in the lesion at present.
  
  
  CONCLUSIONS
  Sclerosing mediastinitis and IgG4-related disease should be included in the differential diagnosis of patients presenting with a mediastinal tumor. However, sclerosing mediastinitis is difficult to diagnose, and it is important to obtain a sufficient amount of tissue to ensure an accurate diagnosis.
authors.affiliation: Second Department of Surgery, University of Occupational and Environmental Health, Kitakyushu, Japan. Electronic address: okasou@med.uoeh-u.ac.jp.
authors.forename: Soichi
authors.initials: S
authors.lastname: Oka
authors.affiliation: Second Department of Surgery, University of Occupational and Environmental Health, Kitakyushu, Japan.
authors.forename: Hidetaka
authors.initials: H
authors.lastname: Uramoto
authors.affiliation: Department of Pathology and Cell Biology, University of Occupational and Environmental Health, Kitakyushu, Japan.
authors.forename: Sohsuke
authors.initials: S
authors.lastname: Yamada
authors.affiliation: Second Department of Surgery, University of Occupational and Environmental Health, Kitakyushu, Japan.
authors.forename: Fumihiro
authors.initials: F
authors.lastname: Tanaka
keywords: Fibrosing mediastinitis; IgG4-related disease; Sclerosing mediastinitis