Hyperostosis Frontalis Interna

Hyperostosis frontalis interna is the thickening of the inner layer of the frontal bone due to the formation of cancellous bone. In hyperostosis frontalis interna, nodular protrusions occur due to the formation of cancellous bone in the inner table of frontal bone. These nodular protrusions may be unilateral or on both sides of the midline but spare midline. Hyperostosis frontalis interna is associated with aging, obesity, menopause, or other endocrinopathies such as diabetes mellitus. The prevalence is shown to be 5%-12% in autopsy series or imaging-based studies. It may be classified according to the extensiveness and appearance of the lesion. The clinical significance is not clear, and hyperostosis frontalis interna is generally an incidental finding detected by imaging methods. But, sometimes headache, dural irritation, or brain atrophy may occur. Neurological or mental signs may be associated with hyperostosis frontalis interna. Underlying endocrinopathies ( acromegaly, primary hyperparathyroidism, osteopetrosis, fibrous dysplasia, or Paget's disease) or malignancies should be excluded. Treatment is supportive and needs to be planned against the underlying disease.