title: Pitfalls in the diagnosis of a tumefactive demyelinating lesion: A case report.
abstract: BACKGROUND
  In rare instances, demyelinating disorders manifest as tumefactive lesions that simulate brain tumors. We report a patient with a space-occupying lesion in the parietal lobe, which presented a serious diagnostic dilemma, between a rare tumefactive demyelinating disease, such as Balo concentric sclerosis and a glioma. This case report highlights important diagnostic clues in the differential diagnosis of Balo concentric sclerosis.
  
  
  METHODS
  A 20-year-old Caucasian woman with acute onset of left-sided weakness and numbness was admitted to hospital with neurologic signs of left-sided hemiparesis and hypoesthesia. Brain magnetic resonance imaging showed a mass lesion of abnormal signal intensity with concentric enhancing rings in the right parietal lobe, without perifocal edema. The characteristic concentric pattern detected on the magnetic resonance images was highly suggestive of Balo disease, and corticosteroids were administered. Evoked potentials, cerebrospinal fluid analysis, and magnetic spectroscopy findings were not specific, and glioma was also included in the differential diagnosis. A stereotactic biopsy was not diagnostic.After one month the patient showed moderate clinical improvement, and during 12 months follow-up, no further relapses occurred. In the follow-up magnetic resonance imaging, the concentric pattern had completely disappeared, and only a low-signal, gliotic lesion remained.
  
  
  CONCLUSIONS
  We hope this case presentation will advance our understanding of clinical and radiologic appearance of Balo concentric sclerosis, which is a rare demyelinating disease. Although this is a specific entity, it has a broader clinical impact across medicine, because it must be differentiated from other space-occupying lesions in the central nervous system.
authors.affiliation: Department of CT and MRI, Children's Hospital, "Agia Sophia'', Thivon and Papadiamantopoulou Street, Athens, Greece. mmgavra@yahoo.com.
authors.forename: Maria
authors.initials: M
authors.lastname: Gavra
authors.forename: Efstathios
authors.initials: E
authors.lastname: Boviatsis
authors.forename: Lampis C
authors.initials: LC
authors.lastname: Stavrinou
authors.forename: Damianos
authors.initials: D
authors.lastname: Sakas