hyperostosis frontalis interna

overgrowth of bone at the inner table of the frontal bone

usually bilateral and symmetrical
chiefly in females > 35 y.o.
no clinical siginificance
unknown etiology
irregular cortical thickening of the frontal area
spares areas occupied by superior sagital sinus and venous channels
may be 1 cm or thicker
occasionaly extends to parietal bones and orbital roofs
hyperostosis calvariae diffusa:
- variant of HFI: more diffuse thickening of vault (involving both tables)