Eosinophilic granuloma or histiocytosis X is most often seen in children aged 1 to 15  with the peak incidence from 1 to 4 years of age.

Characteristic appearance in the skull:

• punched out lytic lesions without sclerotic rim
• double contour or bevelled edge appearance may be seen due to asymmetrical involvement of the inner versus the outer table (hole within a hole sign), best seen in the VR images.