Hyperostosis Frontalis Interna

General Considerations

• Occurs mostly in post-menopausal females over 35 years of age
• Thickening of the inner table of the skull
• Unknown etiology although its presence in post-menopausal women suggest possible hormonal influence

Clinical Findings

• No known clinical significance
• May be more prevalent with obesity

Imaging Findings

• Bilateral and symmetrical
• Cortical thickening that affects primarily frontal bone
  • May occasionally extend to parietal bones
• Characteristically does not extend across the midline at the sagittal sinus
• May appear flat or nodular

Differential Diagnosis

• Should not be confused with hyperostosis from tumor or metastatic disease, Paget disease or fibrous dysplasia

Hyperostosis frontalis interna. Frontal view of skull on left shows sclerosis in a patchy almost nodular appearance (blue arrows) which characteristically does not cross the midline (black arrow). On the lateral view on the right, the hyperostosis is confined to the frontal bone (white arrow).
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Prevalence of hyperostosis frontalis interna in relation to body weight. Verdy M,  Guimond J, Fauteux P and Aube M. The American Journal of Clinical Nutrition 31: Nov 1978, pp. 2002-2004.