Phakomatoses are a group of neurocutaneous disorders characterised by involvement of structures that arise from the embryonic ectoderm (thus central nervous system, skin and eyes). Other organs may also be involved

Pathology

It is sporadic with no definite identifiable hereditary component ⁵.

The leptomeningeal haemangioma results in a vascular steal affecting the subjacent cortex and white matter producing localised ischaemia. The majority of cases (~ 80%) have unihemispherical involvement.

It is a type of craniofacial arteriovenous metameric syndrome (CAMS)

Associations

• 
  coarctation of aorta ¹⁰
  
• 
  paragangliomas ⁹ 
  

Radiographic features

Plain film

Skull x-rays were historically useful and capable of identifying the gyriform calcification of the subcortical white matter although they no longer play a significant role in the diagnosis or management of this condition. The finding usually becomes evident between 2 and 7 years of age ².

CT

• 
  detects subcortical calcification at an earlier age than plain film and can also demonstrate associated parenchymal volume loss
  
• 
  appearance liken to 'tram-track' in nature
  
• 
  calvarial and regional sinus enlargement may be evident
  
• 
  ipsilateral choroid plexus may be enlarged
  
• 
  in severe cases a Dyke-Davidoff-Masson appearence may be seen