Diffuse cranial vault hyperostosis associated with long‐term antiepileptic therapy: Autopsy findings and differential diagnostic considerations

Diffuse cranial vault hyperostosis is an uncommon finding and may present a diagnostic challenge in clinical and forensic practice. We report the case of a 53-year-old woman with a long-standing history of epilepsy treated with phenytoin and sodium valproate who collapsed at home suddenly and died despite resuscitative efforts. Post-mortem examination revealed marked, symmetrical thickening of the frontal, parietal, and occipital bones, with cranial vault thickness reaching approximately 20 mm. Histological analysis demonstrated expansion of the diploë with preserved lamellar architecture and absence of marrow hyperplasia, while examination of the dura mater revealed focal fibrosis and ossification. No evidence of trauma, neoplasia, metabolic bone disease, or hematologic disorder was identified. In the absence of alternative etiologies and in the context of prolonged antiepileptic drug exposure, a medication-related cranial remodeling process was considered the most plausible explanation, most plausibly associated with chronic phenytoin exposure. Death was attributed to recent myocardial ischemia in the setting of pneumonia and cerebral atrophy. This case underscores the importance of integrated clinicopathological correlation when evaluating unusual cranial thickening and highlights the forensic relevance of recognizing medication-associated skeletal remodeling to avoid diagnostic misinterpretation.