title: Dermoid cyst of the posterior fossa associated with congenital dermal sinus in a child.
abstract: BACKGROUND
  Intracranial dermoid cysts are congenital benign neoplasms. Hydrocephalus and abscess as the principal manifestations of the posterior fossa dermoid cyst are rare. We present a case of obstructive hydrocephalus and abscess induced by an adjacent dermoid cyst with occipital dermal sinus.
  
  
  METHODS
  A 2-year-old girl presented with headache and vomiting. Physical examination showed nothing abnormal except for a small subcutaneous nodule above the occipital protuberance with a small skin opening. She had no neurological deficits. Neuroradiological studies including CT and MRI showed a cyst located in the posterior fossa. The cyst in the posterior fossa with occipital dermal sinus was diagnosed. She was treated by radical excision of the occipital cyst through a suboccipital approach, and was followed up.
  
  
  RESULTS
  Histopathologic examination suggested a dermoid cyst with an abscess. Bacterial investigation revealed Staphylococcus epidermidis, and appropriate systemic antibiotic therapy was given. The child recovered and a 2-year follow-up was uneventful.
  
  
  CONCLUSIONS
  Posterior fossa dermoid cyst should be considered in all children with occipital skin lesions, especially dermal sinus. CT and MRI scan are helpful in the diagnosis of the lesion. Neurosurgical treatment of the lesion should be planned early to prevent infections such as abscess and meningitis.
authors.affiliation: Departments of Pediatric Neurosurgery, Tianjin Children's Hospital, Tianjin 300074, China. tjpns@126.com
authors.forename: Chun-Quan
authors.initials: CQ
authors.lastname: Cai
authors.forename: Qing-Jiang
authors.initials: QJ
authors.lastname: Zhang
authors.forename: Xiao-Li
authors.initials: XL
authors.lastname: Hu
authors.forename: Chun-Xiang
authors.initials: CX
authors.lastname: Wang
mesh_terms: D000900:Anti-Bacterial Agents / Q000627:therapeutic use; D001922:Brain Abscess / Q000188:drug therapy / Q000209:etiology* / Q000382:microbiology; D002443:Ceftriaxone / Q000627:therapeutic use; D002675:Child, Preschool; D003884:Dermoid Cyst / Q000150:complications* / Q000175:diagnosis / Q000601:surgery; D005260:Female; D006801:Humans; D006849:Hydrocephalus / Q000209:etiology*; D015192:Infratentorial Neoplasms / Q000150:complications* / Q000175:diagnosis / Q000601:surgery; D008279:Magnetic Resonance Imaging; D016136:Spina Bifida Occulta / Q000150:complications* / Q000175:diagnosis / Q000601:surgery; D013203:Staphylococcal Infections; D013212:Staphylococcus epidermidis; D014057:Tomography, X-Ray Computed
chemical_list: D000900:Anti-Bacterial Agents; D002443:Ceftriaxone