title: Spontaneous Regression of a Third Ventricle Colloid Cyst.
abstract: BACKGROUND
  Colloid cysts represent 0.5%-1% of intracranial tumors and most commonly occur in the third ventricle near the Monro foramen. Although benign, if the lesion obstructs the foramen abruptly, sudden death may ensue. Evolution of these cysts is poorly understood. Spontaneous regression has been reported in only 2 other cases. Management of such cysts depends on whether the cyst continues to grow, its location, and clinical presentation. Incidental asymptomatic colloid cysts are typically followed with neuroimaging surveillance.
  
  
  METHODS
  We present a case of an incidental third ventricle colloid cyst in a 46-year-old patient who was managed conservatively with neuroimaging surveillance. Thereafter, she started developing some working memory deficits and intermittent headaches, with the cyst volume increasing, leading to the decision to perform a resection. However, the cyst underwent spontaneous regression before the scheduled surgery date, 3 years after initial diagnosis.
  
  
  CONCLUSIONS
  This case confirms that some colloid cysts could regress spontaneously. Disappearance of the cyst is not necessarily accompanied by clinical worsening, as was reported by other investigators who noted deteriorating neurologic deficits as a result of worsening hydrocephalus. Assuming the cysts rupture, some patients tolerate the contents of the cyst leaking into the ventricular system, whereas others may mount an inflammatory reaction, causing a disruption in cerebrospinal fluid flow. In addition, it is still unclear what factors increase the likelihood of cysts to suddenly rupture.
authors.affiliation: Department of Neurosurgery, Paris Descartes University, Paris, France; Department of Neurosurgery, University of Texas Southwestern, Dallas, Texas, USA.
authors.forename: Sophie M
authors.initials: SM
authors.lastname: Peeters
authors.affiliation: Department of Neurosurgery, Thomas Jefferson University Hospital, Philadelphia, Pennsylvania, USA.
authors.forename: Badih
authors.initials: B
authors.lastname: Daou
authors.affiliation: Department of Neurosurgery, Thomas Jefferson University Hospital, Philadelphia, Pennsylvania, USA.
authors.forename: Pascal
authors.initials: P
authors.lastname: Jabbour
authors.affiliation: Department of Radiology, Bicetre University Hospital, France.
authors.forename: Alexandre
authors.initials: A
authors.lastname: Ladoux
authors.affiliation: Department of Neurosurgery, Paris Descartes University, Paris, France; Department of Neurosurgery, University of Texas Southwestern, Dallas, Texas, USA; Department of Radiology, Bicetre University Hospital, France; Department of Neurosurgery, Sainte-Anne University Hospital, Paris, France. Electronic address: g.abi-lahoud@ch-sainte-anne.fr.
authors.forename: Georges
authors.initials: G
authors.lastname: Abi Lahoud
mesh_terms: D000328:Adult; D056364:Colloid Cysts / Q000000981:diagnostic imaging* / Q000473:pathology*; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D009365:Neoplasm Regression, Spontaneous
keywords: Brain; Cyst; MRI; Tumor