Short-term aneurysm formation and rupture due to septic embolism diagnosed with a thrombus retrieved from another occluded artery

BACKGROUND: In rare cases, septic embolism is diagnosed on the basis of pathological findings of retrieved thrombi. Infected aneurysms can rapidly form and rupture after septic embolism, leading to a poor prognosis. We report a case of subcortical hemorrhage due to an infected aneurysm forming shortly after septic embolism in the left anterior cerebral artery. CASE DESCRIPTION: In this case, the diagnosis of septic embolism was made on the basis of pathological findings of a thrombus retrieved from the simultaneously occluded left middle cerebral artery, and endovascular embolization of the infected aneurysm was performed. CONCLUSION: The pathological findings of a retrieved thrombus were useful for making a diagnosis of septic embolism. The possibility of short-term formation and rupture of an infected aneurysm after septic embolism should be noted. Endovascular embolization of occluded vessels due to septic embolism may prevent aneurysm formation and subsequent bleeding.