title: Role of MR imaging in the diagnosis of complicated arachnoid cyst.
abstract: BACKGROUND
  Arachnoid cysts are intra-arachnoidal cerebrospinal fluid collections that are usually asymptomatic, however, they may become acutely symptomatic due to enlargement of the cyst or the presence of hemorrhage.
  
  
  METHODS
  We report a case of a child presenting with a 3-week history of headaches, nausea, and vision problems. There was no history of trauma. MRI clearly demonstrated a left middle cranial fossa arachnoid cyst with associated subacute intracystic and subdural hematoma that was causing mass effect and required surgery.
  
  
  RESULTS
  This lesion was isodense to the brain on CT.
  
  
  CONCLUSIONS
  We focus on the importance of MR imaging in the differentiation of these subacute/early chronic hemorrhagic collections that may be overlooked with CT.
authors.affiliation: Department of Radiology, The University of Texas, Health Science Center, San Antonio 78284-7800, USA.
authors.forename: R
authors.initials: R
authors.lastname: Ibarra
authors.forename: P P
authors.initials: PP
authors.lastname: Kesava
mesh_terms: D016080:Arachnoid Cysts / Q000150:complications / Q000175:diagnosis* / Q000601:surgery; D001921:Brain / Q000473:pathology*; D002648:Child; D003937:Diagnosis, Differential; D006801:Humans; D020300:Intracranial Hemorrhages / Q000175:diagnosis* / Q000209:etiology / Q000601:surgery; D008279:Magnetic Resonance Imaging; D008297:Male; D015203:Reproducibility of Results