title: Incidence and pattern of radiological central nervous system Langerhans cell histiocytosis in children: a population based study.
abstract: BACKGROUND
  Patients with Langerhans cell histiocytosis (LCH) may develop neurodegeneration and other central nervous system (CNS) dysfunctions revealed by brain magnetic resonance imaging (MRI). We estimated the incidence and pattern of pathological brain MRI findings in a well-defined, population-based cohort of children with LCH.
  
  
  METHODS
  Among children under 15 years of age diagnosed with LCH in the Stockholm County during 1992-2001, brain MRI was performed at a single center in children with clinical and/or laboratory signs of CNS involvement, including endocrine dysfunction.
  
  
  RESULTS
  Out of the 29 children (16 males, 13 females) diagnosed with LCH, brain MRI was performed based on clinical indications in 16 children (55%) with either abnormal endocrine findings (n = 6), such as diabetes insipidus (n = 5), low IGF-1 (n = 1), or panhypopituitarism (n = 1), or clinical CNS symptoms (n = 10). CNS MRI abnormalities were demonstrated in eight children (28%), at a median time of 3.5 years after LCH diagnosis (range 1-11.4 years). Altogether 7 of the 29 children (24%) had MRI findings associated with neurodegeneration, corresponding to a minimal incidence of 2.1/10(6) children per year. Neurodegenerative abnormalities tended to be more frequent in patients with craniofacial involvement (P = 0.12).
  
  
  CONCLUSIONS
  The minimal annual incidence rate of neurodegenerative associated radiographic findings in LCH is estimated at 2.1/10(6) children (24% of all children with LCH). An important question is whether all patients with LCH, or certain forms of LCH, should be recommended for a late follow-up examination including MRI. In patients with CNS-LCH, neurological, neuropsychological, neurophysiological, neurochemical and neuroradiological follow-up assessment is suggested.
authors.affiliation: Childhood Cancer Research Unit, Karolinska University Hospital, Department of Women's and Children's Health, Karolinska Institutet, Stockholm, Sweden. Evaldas.Laurencikas@ki.se
authors.forename: Evaldas
authors.initials: E
authors.lastname: Laurencikas
authors.forename: Désirée
authors.initials: D
authors.lastname: Gavhed
authors.forename: Helen
authors.initials: H
authors.lastname: Stålemark
authors.forename: Ingrid
authors.initials: I
authors.lastname: van't Hooft
authors.forename: Daniela
authors.initials: D
authors.lastname: Prayer
authors.forename: Nicole
authors.initials: N
authors.lastname: Grois
authors.forename: Jan-Inge
authors.initials: JI
authors.lastname: Henter
mesh_terms: D001921:Brain / Q000473:pathology; D002493:Central Nervous System Diseases / Q000453:epidemiology* / Q000473:pathology*; D002648:Child; D002675:Child, Preschool; D005260:Female; D006646:Histiocytosis, Langerhans-Cell / Q000453:epidemiology* / Q000473:pathology*; D006801:Humans; D015994:Incidence; D007223:Infant; D008279:Magnetic Resonance Imaging; D008297:Male