Hyperostosis frontalis interna
Updates to Article Attributes
Hyperostosis frontalis interna is characterised by benign overgrowth of the inner table of the frontal bone. The aetiology is unknown. The The condition is generally an incidental finding 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).
Hyperostosis calvariae diffusa and hyperostosis frontoparietalis are related entities.
Epidemiology
Post mortem-mortem studies report a prevalence of 12% 3. It is most common in women over the age of 65, with 87% of severe hyperostosis frontalis interna occurring in this cohort of patients 3.
Clinical presentation
As hyperostosis frontalis interna is usually an incidental finding of no clinical significance, patients are generally asymptomatic. Compression by calvarial thickening may lead to cerebral atrophy and may present with cognitive impairment, neuropsychiatric symptoms, headachesheadache, and epilepsy 1,3,3.
Pathology
The aetiology and pathogenesis are not well understood, although many theories have been proposed. These include a genetic predisposition, angiosomes of numerous vascular anastomoses on the frontal bone of the calvaria, and the oestrogen theory 3. Nodular Nodular endocranial remodelling may result in compression of the cerebrum.
Classification
Hyperostosis frontalis interna is classified into four grades of severity based on Hershkovitz's morphological and histopathological findings 1. The Hershkovitz classification was modified to include a fifth grade of severity after a cadaveric study in 2011 described hyperostotic findings at the falx cerebri 1,3.
type A: endocranial frontal bone elevations less than 10 mm in diameter
type B: nodular bony formations occupying less than 25% of the frontal bone
type C: nodular bony formations occupying up to 50% of the frontal bone
type D: continuous nodular bony formations involving more than 50% of the frontal endocranium
type E: severe hyperostosis frontalis interna with soft tissue expansion
History and etymology
It was first described in 1719 by Italian anatomist Giovanni Battista Morgagni as a pathology accompanying virilism and obesity 3.
Associations
It is part of the triad of Morgagni-Stewart-Morel syndrome and and may be encountered in a number of other syndromes 3:
Differential Diagnosis
The differential is that of hyperostosis of the skull and includes:
bone marrow pathology
-<p><strong>Hyperostosis frontalis interna</strong> is characterised by benign overgrowth of the inner table of the frontal bone. 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. </p><p>The importance of this condition stems mainly from the necessity of not mistaking it for pathology (see below).</p><p><a href="/articles/hyperostosis-calvariae-diffusa">Hyperostosis calvariae diffusa</a> and <a href="/articles/hyperostosis-frontoparietalis-1">hyperostosis frontoparietalis</a> are related entities.</p><h4>Epidemiology</h4><p>Post mortem studies report a prevalence of 12% <sup>3</sup>. It is most common in women over the age of 65 with 87% of severe hyperostosis frontalis interna occurring in this cohort of patients <sup>3</sup>.</p><h4>Clinical presentation</h4><p>As hyperostosis frontalis interna is usually an incidental finding of no clinical significance patients are generally asymptomatic. Compression by calvarial thickening may lead to cerebral atrophy and may present with cognitive impairment, neuropsychiatric symptoms, headaches and epilepsy <sup>1,</sup><sup>3</sup>.</p><h4>Pathology</h4><p>The aetiology and pathogenesis are not well understood although many theories have been proposed. These include a genetic predisposition, angiosomes of numerous vascular anastomoses on the frontal bone of the calvaria and the oestrogen theory <sup>3</sup>. Nodular endocranial remodelling may result in compression of the cerebrum.</p><h4>Classification</h4><p>Hyperostosis frontalis interna is classified into four grades of severity based on Hershkovitz's morphological and histopathological findings <sup>1</sup>. The Hershkovitz classification was modified to include a fifth grade of severity after a cadaveric study in 2011 described hyperostotic findings at the falx cerebri <sup>1,3</sup>.</p><ul>-<li>-<strong>type A:</strong> endocranial frontal bone elevations less than 10 mm in diameter</li>-<li>-<strong>type B:</strong> nodular bony formations occupying less than 25% of the frontal bone</li>-<li>-<strong>type C:</strong> nodular bony formations occupying up to 50% of the frontal bone</li>-<li>-<strong>type D:</strong> continuous nodular bony formations involving more than 50% of the frontal endocranium</li>-<li>-<strong>type E:</strong> severe hyperostosis frontalis interna with soft tissue expansion</li>-</ul><h4>History and etymology</h4><p>It was first described in 1719 by <strong>Morgagni </strong>as a pathology accompanying virilism and obesity <sup>3</sup>.</p><h4>Associations</h4><p>It is part of the triad of <a href="/articles/morgagni-stewart-morel-syndrome">Morgagni syndrome</a> and may be encountered in a number of other syndromes <sup>3</sup>:</p><ul>-<li>-<a href="/articles/troell-junet">Troell-Junet</a><a href="/articles/troell-junet-syndrome"> syndrome</a>-</li>-<li>-<a href="/articles/frolich">Fr</a><a href="/articles/fr-lich-syndrome">ö</a><a href="/articles/frolich">lich</a><a href="/articles/fr-lich-syndrome"> syndrome</a>-</li>-<li><a href="/articles/klippel-tr-naunay-weber-syndrome">Klippel-Trénaunay-Weber syndrome</a></li>-</ul><h4>Differential Diagnosis</h4><p>The differential is that of <a href="/articles/hyperostosis-of-the-skull-differential">hyperostosis of the skull</a> and includes:</p><ul>-<li><a href="/articles/paget-disease-bone">Paget disease</a></li>-<li><a href="/articles/fibrous-dysplasia">fibrous dysplasia</a></li>-<li><a href="/articles/sclerotic-metastases">sclerotic metastases</a></li>-<li><a href="/articles/meningioma">meningioma</a></li>-<li><a href="/articles/acromegaly">acromegaly</a></li>-<li>bone marrow pathology</li>- +<p><strong>Hyperostosis frontalis interna</strong> is characterised by benign overgrowth of the inner table of the <a href="/articles/frontal-bone" title="Frontal bone">frontal bone</a>. The aetiology is unknown. The condition is generally an incidental finding of no clinical significance. 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. </p><p>The importance of this condition stems mainly from the necessity of not mistaking it for pathology (see below).</p><p><a href="/articles/hyperostosis-calvariae-diffusa">Hyperostosis calvariae diffusa</a> and <a href="/articles/hyperostosis-frontoparietalis-1">hyperostosis frontoparietalis</a> are related entities.</p><h4>Epidemiology</h4><p>Post-mortem studies report a prevalence of 12% <sup>3</sup>. It is most common in women over the age of 65, with 87% of severe hyperostosis frontalis interna occurring in this cohort of patients <sup>3</sup>.</p><h4>Clinical presentation</h4><p>As hyperostosis frontalis interna is usually an incidental finding of no clinical significance, patients are generally asymptomatic. Compression by calvarial thickening may lead to cerebral atrophy and may present with cognitive impairment, neuropsychiatric symptoms, headache, and <a href="/articles/epilepsy" title="Epilepsy">epilepsy</a> <sup>1,3</sup>.</p><h4>Pathology</h4><p>The aetiology and pathogenesis are not well understood, although many theories have been proposed. These include a genetic predisposition, angiosomes of numerous vascular anastomoses on the frontal bone of the calvaria, and the oestrogen theory <sup>3</sup>. Nodular endocranial remodelling may result in compression of the cerebrum.</p><h4>Classification</h4><p>Hyperostosis frontalis interna is classified into four grades of severity based on Hershkovitz's morphological and histopathological findings <sup>1</sup>. The Hershkovitz classification was modified to include a fifth grade of severity after a cadaveric study in 2011 described hyperostotic findings at the <a href="/articles/falx-cerebri" title="Falx cerebri">falx cerebri</a> <sup>1,3</sup>.</p><ul>
- +<li><p><strong>type A:</strong> endocranial frontal bone elevations less than 10 mm in diameter</p></li>
- +<li><p><strong>type B:</strong> nodular bony formations occupying less than 25% of the frontal bone</p></li>
- +<li><p><strong>type C:</strong> nodular bony formations occupying up to 50% of the frontal bone</p></li>
- +<li><p><strong>type D:</strong> continuous nodular bony formations involving more than 50% of the frontal endocranium</p></li>
- +<li><p><strong>type E:</strong> severe hyperostosis frontalis interna with soft tissue expansion</p></li>
- +</ul><h4>History and etymology</h4><p>It was first described in 1719 by Italian anatomist <strong>Giovanni Battista Morgagni </strong>as a pathology accompanying virilism and obesity <sup>3</sup>.</p><h4>Associations</h4><p>It is part of the triad of <a href="/articles/morgagni-stewart-morel-syndrome">Morgagni-Stewart-Morel syndrome</a> and may be encountered in a number of other syndromes <sup>3</sup>:</p><ul>
- +<li><p><a href="/articles/troell-junet">Troell-Junet syndrome</a></p></li>
- +<li><p><a href="/articles/frolich">Fr</a><a href="/articles/fr-lich-syndrome">ö</a><a href="/articles/frolich">lich syndrome</a></p></li>
- +<li><p><a href="/articles/klippel-trenaunay-syndrome-1">Klippel-Trénaunay-Weber syndrome</a></p></li>
- +</ul><h4>Differential Diagnosis</h4><p>The differential is that of <a href="/articles/hyperostosis-of-the-skull-differential">hyperostosis of the skull</a> and includes:</p><ul>
- +<li><p><a href="/articles/paget-disease-bone">Paget disease</a></p></li>
- +<li><p><a href="/articles/fibrous-dysplasia">fibrous dysplasia</a></p></li>
- +<li><p><a href="/articles/sclerotic-metastases">sclerotic metastases</a></p></li>
- +<li><p><a href="/articles/meningioma">meningioma</a></p></li>
- +<li><p><a href="/articles/acromegaly">acromegaly</a></p></li>
- +<li><p>bone marrow pathology</p></li>
Unable to process the form. Check for errors and try again.