[Autopsy case of cerebral embolism with lung cancer and atrial fibrillation in which the left atrium may have become an incubator for a tumor embolus].

An 82-year-old man with advanced lung cancer who had declined aggressive therapy was transferred to our hospital due to sudden-onset consciousness disturbance, global aphasia, and right hemiplegia. An electrocardiogram showed atrial fibrillation, and brain MRI and MRA revealed acute ischemic lesions of the left hemisphere and occlusion of the left internal carotid artery (ICA), respectively. We diagnosed acute ischemic stroke due to left ICA occlusion and performed endovascular thrombectomy, which resulted in complete recanalization of the left ICA after retrieval of the culprit embolus. Pathological examination of the retrieved thrombus revealed the presence of tumor tissue, as well as fibrin or red blood cells. Treatment was continued after admission, but the patient died of respiratory failure on day 40 of hospitalization. Autopsy revealed invasion of the tumor in the pulmonary vein, but not in the wall of the left atrium where thrombi were present. However, pathological examination of these thrombi in the left atrium revealed tumor tissue, along with fibrin or red blood cells. These findings suggest that the wall of the left atrium, in which lung cancer had not invaded, may be an incubator of a mixed embolus containing tumor tissue and thrombi in a case of cerebral embolism associated with both lung cancer and atrial fibrillation.