A 57-year-old white woman, with history of hydatidiform mole 2 years earlier, was evaluated at our stroke center for the acute onset of intense cephalgia, vomiting, and aphasia. Recent medical history was significant for a vertebrobasilar transient ischemic attack 1 month earlier with a negative etiologic evaluation and negative vessel imaging and transesophageal echocardiography (TEE). A treatment by aspirin 160 mg was then started. On admission, neurological examination revealed a global aphasia and right homonymous hemianopsia. The National Institutes of Health Stroke Scale score was 8. She had no fever. Cardiovascular examination revealed a systolic murmur. Pulmonary auscultation was normal. A computed tomographic brain scan showed a left lobar temporal intracerebral hematoma with a subarachnoid hemorrhage in the ipsilateral sylvian fissure. Cerebral angiography and arteriography showed no vascular abnormality. Brain MRI showed a hemorrhagic infarction in the left middle cerebral artery territory and revealed several subacute infarctions in other vascular territories (Figure 1). Magnetic resonance angiography was normal. Coagulation tests involving fibrinogen, prothrombin time, activated partial thromboplastin time were normal. These multiple infarcts raised concern for a cardioembolic etiology to her stroke. The cardiac monitoring showed no arrhythmia. The transthoracic echocardiography showed an echogenic structure in the left atrium that was not clearly visualized ( Figure 2). TEE revealed a 3-cm thrombus in the left atrium extending into a pulmonary vein ( Figure 3, Movie I in the online-only Data Supplement). Anticoagulation by unfractionated heparin was started. Chest computed tomography and angiography confirmed the presence of the thrombus in the right inferior pulmonary vein contiguous to an invasive pulmonary mass of the right inferior lobe infiltrating the right inferior pulmonary vein (Figure 4). Abdominal and pelvic computed tomography were normal. Because the patient had a past medical history of hydatidiform mole, serum β-human chorionic gonadotrophin was measured. Its level was highly increased at 155.2 IU/L (normal β-human chorionic gonadotrophin level is <2 IU/L). Those investigations led to the diagnosis of a pulmonary metastasis of a choriocarcinoma.A transbronchial lung biopsy was performed, but the biopsy material was not specific. Because increased β-human chorionic gonadotrophin is a very sensitive and specific test for the diagnosis of choriocarcinoma, histopathologic proof of choriocarcinoma is not always required to initiate therapy.1 The patient was then transferred to the oncology department where combination chemotherapy (etoposide, methotrexate, actinomycin D, cyclophosphamide, vincristine) was initiated. One month later the patient was functionally independent (modified Rankin Scale=2) and her National Institutes of Health Stroke Scale score was 3. At 3 months, the control TEE showed a persistent thrombus in the left atrium and the MRI was stable. Anticoagulation treatment was...