Full Penetrance of Morgagni-Stewart-MorelSyndrome in a 75-Year-Old Woman: Case Report and Review of the Literature. Morgagni-Stewart-Morelsyndrome is defined as the presence of hyperostosis frontalis interna, variably associated with metabolic, endocrine, and neuropsychiatric disorders. The possible cause-effect relationship of these associations remains uncertain. A 75-year-old woman presented with severe frontal headache and a history of psychotic disorders. On instrumental examination she was found to have extensive frontal hyperostosis and cortical atrophy. These findings, associated to the metabolic and neuropsychiatric pattern of the patient, are consistent with a high penetrance of Morgagni-Stewart-Morelsyndrome. In this clinical case seminar, we summarize the current