title: Composite paraganglioma-ganglioneuroma in the retroperitoneum.
abstract: BACKGROUND
  Paragangliomas occur most commonly in head and neck region and much less frequently, they are found in the retroperitoneum. Composite paraganglioma-ganglioneuroma of the retroperitoneum is very rare.
  
  
  METHODS
  We present an unusual case of retroperitoneal composite paraganglioma-ganglioneuroma discovered on computed tomography in a 63-year-old female patient. Routine hematological examination and biochemical tests were within normal limits. Plasma adrenaline was 0.042 ng/ml, plasma noradrenaline 0.341 ng/ml, and plasma dopamine <0.01 ng/ml. An abdominal contrast-enhanced CT scan and magnetic resonance imaging revealed a 6.5 cm heterogeneous retroperitoneal mass with a cystic component. The retroperitoneal tumor accumulated (131)I-Metaiodobenzylguanidine ((131)I-MIBG) 48 hours after radioisotope injection. Under the diagnosis of paraganglioma in the retroperitoneum, the patient underwent surgery. The resected tumor (6.5 x 5 x 3 cm) was solid and easily removed en bloc. The cut surface of the tumor and histology revealed two different components in the tumor: paraganglioma centrally and ganglioneuroma on the periphery. She remains disease-free 18 months after surgery.
  
  
  CONCLUSIONS
  This case reminds us that neuroendocrine tumor should be included in the differential diagnosis of a retroperitoneal mass although composite paraganglioma-ganglioneuroma in the retroperitoneum is very rare.
authors.affiliation: Division of Gastroenterology, Sumitomo Besshi Hospital, 3-1 Ohji-cho, Niihama 7928543, Japan. hirasaki@icknet.ne.jp
authors.forename: Shoji
authors.initials: S
authors.lastname: Hirasaki
authors.forename: Hiromitsu
authors.initials: H
authors.lastname: Kanzaki
authors.forename: Masato
authors.initials: M
authors.lastname: Okuda
authors.forename: Seiyuu
authors.initials: S
authors.lastname: Suzuki
authors.forename: Tetsuji
authors.initials: T
authors.lastname: Fukuhara
authors.forename: Toshihito
authors.initials: T
authors.lastname: Hanaoka
mesh_terms: D019797:3-Iodobenzylguanidine; D003937:Diagnosis, Differential; D005260:Female; D005729:Ganglioneuroma / Q000175:diagnosis* / Q000601:surgery; D006801:Humans; D033162:Incidental Findings; D008279:Magnetic Resonance Imaging; D008875:Middle Aged; D010235:Paraganglioma / Q000175:diagnosis* / Q000601:surgery; D019275:Radiopharmaceuticals; D012186:Retroperitoneal Neoplasms / Q000175:diagnosis* / Q000601:surgery; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome
chemical_list: D019275:Radiopharmaceuticals; D019797:3-Iodobenzylguanidine