title: Posterior mediastinal ganglioneuroma with peripheral replacement by white and brown adipocytes resulting in diagnostic fallacy from a false-positive 18F-2-fluoro-2-deoxyglucose-positron emission tomography finding: a case report.
abstract: BACKGROUND
  Ganglioneuroma is a rare tumor in the posterior mediastinum; fat-containing ganglioneuromas are rarely reported. The present case report documents a brown fat-containing, posterior mediastinal ganglioneuroma, which has not been reported previously. Radiological examination, in particular 18F-2-fluoro-2-deoxyglucose-positron emission tomography, suggested that the tumor had low-grade malignant potential. This led to uncertainty at preoperative diagnosis.
  
  
  METHODS
  An asymptomatic 66-year-old Japanese woman with no significant past medical history was referred for the evaluation of a posterior mediastinal mass. Although its size had not changed in the past 5 years, a malignant lipomatous tumor could not be excluded due to the presence of intratumoral fat and increased 18F-2-fluoro-2-deoxyglucose uptake observed by positron emission tomography imaging. A computed tomography-guided core-needle biopsy revealed a mixture of mature adipocytes, spindle-shaped cells, and fibrotic stroma. Definite diagnosis was not possible, and surgical resection was performed. Three years after the surgery, she remains disease-free.
  
  
  CONCLUSIONS
  Histological diagnosis of the surgically resected mass confirmed ganglioneuroma with substantial amounts of white and brown adipose tissues in peripheral areas. The existence of both ganglion cells and brown fat tissue intensified the accumulation of 18F-2-fluoro-2-deoxyglucose, resulting in a false-positive result by positron emission tomography. Considering this, ganglioneuroma should not be excluded either clinically or pathologically in fat-containing, posterior mediastinal tumors.
authors.affiliation: Section of Oncopathology and Regenerative Biology, Department of Pathology, Faculty of Medicine, University of Miyazaki, 5200 Kihara, Kiyotake, Miyazaki 889-1692, Japan. kenji_yorita@med.miyazaki-u.ac.jp.
authors.forename: Kenji
authors.initials: K
authors.lastname: Yorita
authors.forename: Akihiro
authors.initials: A
authors.lastname: Yonei
authors.forename: Takanori
authors.initials: T
authors.lastname: Ayabe
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Nakada
authors.forename: Ken
authors.initials: K
authors.lastname: Nakashima
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Fukushima
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Kataoka
mesh_terms: D052437:Adipocytes, Brown / Q000000981:diagnostic imaging / Q000473:pathology*; D052438:Adipocytes, White / Q000000981:diagnostic imaging / Q000473:pathology*; D000368:Aged; D062005:Biopsy, Large-Core Needle; D005189:False Positive Reactions; D005260:Female; D019788:Fluorodeoxyglucose F18; D005729:Ganglioneuroma / Q000000981:diagnostic imaging* / Q000473:pathology; D006801:Humans; D008479:Mediastinal Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology; D049268:Positron-Emission Tomography; D019275:Radiopharmaceuticals
chemical_list: D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18