Hyperostosis frontalis interna is characterised by benign overgrowth of the inner table of the frontal bone. It is seen most commonly in older females. The aetiology is unknown. The condition is generally of no clinical significance and an incidental finding. It is typically bilateral and symmetrical, and may extend to involve the parietal bones. The skull thickening may be sessile or nodular, and may affect the bone in a focal or diffuse manner.
The importance of this condition stems mainly from the necessity of not mistaking it for pathology. (see below)
It is part of the triad of Morgagni syndrome.
The differential is that of hyperostosis of the skull and includes: