Mycotic aneurysm presenting as subdural empyema: illustrative case.

BACKGROUND: Mycotic aneurysms (MAs) are rare intracranial pathologies. They are associated with spontaneous rupture, which is often the first presenting sign. Subarachnoid hemorrhage and intraparenchymal hemorrhage are the most common sequelae of ruptured MAs, with subdural hematoma being an atypical presentation. The presentation of an MA as a subdural empyema has not yet been reported in the literature. OBSERVATIONS: The authors discussed a 68-year-old man who presented with subdural empyema and received surgery for evacuation. He was found to have a ruptured mycotic aneurysm intraoperatively. LESSONS: This case demonstrated a rare and atypical presentation of an MA.