title: Endolymphatic sac tumor in a 4-year-old boy.
abstract: BACKGROUND
  Endolymphatic sac tumors (ELST) are rare, low-grade, locally aggressive papillary neoplasms. We present a case of a 4-year-old boy with an ELST, the youngest described in the literature.
  
  
  METHODS
  A boy presented with a right-sided serous otitis media and sudden-onset right facial nerve palsy. An audiogram revealed right-sided profound sensorineural hearing loss. Radiographic imaging demonstrated a 3-cm expansile lytic lesion along the posterior face of the petrous bone.
  
  
  RESULTS
  The patient initially underwent a right transmastoid-infralabyrinthine biopsy. Pathologic examination revealed a papillary lesion suspicious for an ELST. Subsequently, a transtemporal-transcochlear approach with intra-and extradural resection of the tumor was performed. The facial nerve was dissected and transposed anteriorly and preserved. Histopathologic and immunohistochemical studies confirmed the ELST. At his 6-month follow up, there is no evidence of recurrence and the facial nerve function has returned to Grade II palsy.
  
  
  CONCLUSIONS
  ELST are rare tumors of the temporal bone. This is the youngest case of ELST reported. Presentation, evaluation, and management of ELST is discussed.
authors.affiliation: Department of Otorhinolaryngology-Head and Neck Surgery, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, USA.
authors.forename: Michael E
authors.initials: ME
authors.lastname: Kupferman
authors.forename: Douglas C
authors.initials: DC
authors.lastname: Bigelow
authors.forename: David F
authors.initials: DF
authors.lastname: Carpentieri
authors.forename: Larissa T
authors.initials: LT
authors.lastname: Bilaniuk
authors.forename: Ken
authors.initials: K
authors.lastname: Kazahaya
mesh_terms: D000231:Adenocarcinoma, Papillary / Q000175:diagnosis* / Q000601:surgery; D001301:Audiometry, Pure-Tone; D002675:Child, Preschool; D004428:Ear Neoplasms / Q000175:diagnosis* / Q000601:surgery; D007758:Ear, Inner / Q000601:surgery; D004712:Endolymphatic Sac / Q000473:pathology*; D005158:Facial Paralysis / Q000209:etiology; D006319:Hearing Loss, Sensorineural / Q000209:etiology; D006801:Humans; D007150:Immunohistochemistry; D008279:Magnetic Resonance Imaging; D008297:Male; D010034:Otitis Media with Effusion / Q000209:etiology; D014057:Tomography, X-Ray Computed