Recurrent Stroke Due to Metastatic Pulmonary Tumor Emboli as an Important Clinical Entity.

We present an autopsy case of repetitive stroke due to tumor emboli, indistinguishable from thromboembolism with a hypercoagulable state in its clinical course. A 72-year-old man diagnosed with stage IVA oropharyngeal squamous cell carcinoma received chemoradiotherapy. Follow-up imaging revealed mediastinal lymph nodes and pulmonary metastasis. One year later, the patient experienced right arm weakness, and brain magnetic resonance imaging showed acute ischemic lesions in multiple vascular territories. He was diagnosed with paradoxical cerebral embolism due to cancer-associated venous thrombosis and treated with rivaroxaban. However, newly developed cerebral infarcts were confirmed 1 month later. Then, rivaroxaban treatment was switched to subcutaneous unfractionated heparin injection. He was admitted again for stroke recurrence and died of respiratory failure 8 days after admission. Autopsy demonstrated pulmonary metastasis invading the veins and tumor emboli in the culprit cerebral arteries. D-dimer was kept constant at a slightly higher level, ranging from 1 to 3 µg/mL during the course of recurrence. We should consider tumor embolism in the differential diagnosis of recurrent stroke along with pulmonary tumor and resistance to heparin preparations with unchanged D-dimer levels.