title: Radiologic features of primary intracranial ectopic germinomas: Case reports and literature review.
abstract: BACKGROUND
  Germinomas are sensitive to radiation therapy and chemotherapy; therefore, correct imaging diagnosis is crucial for them. However, the imaging findings of germinomas originating from off-midline regions displayed different patterns from those originating from midline areas.
  
  
  METHODS
  The objective of this study is to describe the radiologic features of primary ectopic germinoma. We reviewed the MR and CT findings of 12 patients with histologically proven off-midline ectopic germinomas with off-midline locations.
  
  
  METHODS
  All of these patients underwent conventional MR images and 3 of them underwent diffusion images. Additional CT images were available in 3 patients. Analysis was focused on the shape and entity of tumors in images, signs of hemiatrophy, and the involvement of fibers in diffusion images.
  
  
  RESULTS
  Well-defined (8/12) and ill-defined margin masses (4/12) were identified according to the shape of the mass. Multicystic masses were seen in 11 of the 12 patients. The solid component of the tumors had a high density (3/3) with calcifications (2/3) on CT images, iso- to hypointensity in T2WI (11/12) and restricted diffusion on apparent diffusion coefficient (ADC) maps (3/3). Hemiatrophy was observed in 5 cases and progressive hemiatrophy was observed in 1 case. Other signs included mild peritumoral edema (10/12), and hydrocephalus (7/12). Additionally, infiltration of the corticospinal tract (CST) was identified on diffusion tensor imaging (DTI) (2/2).
  
  
  CONCLUSIONS
  The results indicate that multicysitic entities and hypointensities in solid components on T2WI and hemiatrophy are the imaging features of ectopic germinomas. DTI has potential for assessing CST involvement.
authors.affiliation: Department of Radiology, Guangzhou First People's Hospital, Guangzhou Medical University, Guangzhou, Guangdong Department of Neuroradiology, Tiantan Hospital, Beijing, China.
authors.forename: Xin-Hua
authors.initials: XH
authors.lastname: Wei
authors.forename: Hui-Cong
authors.initials: HC
authors.lastname: Shen
authors.forename: Shou-Xian
authors.initials: SX
authors.lastname: Tang
authors.forename: Cui-Hua
authors.initials: CH
authors.lastname: Gao
authors.forename: Ji-Liang
authors.initials: JL
authors.lastname: Ren
authors.forename: Lin
authors.initials: L
authors.lastname: Ai
authors.forename: Jian-Ping
authors.initials: JP
authors.lastname: Dai
mesh_terms: D000293:Adolescent; D000328:Adult; D001929:Brain Edema / Q000000981:diagnostic imaging; D001932:Brain Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology; D002114:Calcinosis / Q000000981:diagnostic imaging; D002648:Child; D005260:Female; D018237:Germinoma / Q000000981:diagnostic imaging* / Q000473:pathology; D006801:Humans; D006849:Hydrocephalus / Q000000981:diagnostic imaging; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D014057:Tomography, X-Ray Computed; D055815:Young Adult