[A case of intravascular large B-cell lymphoma with rapidly progressive cognitive impairment after cerebral infarction].

A 67-year-old man started to show symptoms of dementia and developed convulsions accompanied by presyncope. Since an old cerebral infarction was found, he was given a diagnosis of symptomatic epilepsy, treated with antiepileptics. Dementia progressed rapidly, resulting in admission to a dementia ward. There were no physical abnormalities, and only slight elevations of LDH and CRP were noted. He suddenly developed a fever between 38°C and 39°C. Only the serum concentration of soluble IL-2 receptor was elevated at 6,430 U/L. Although a malignant tumor of the lymphatic system was suspected, there was no swelling noted in the superficial lymph nodes. The patient suddenly developed hypoxemia, thrombocytopenia, and an increase in fibrin degradation products. Pulmonary thromboembolism was suspected, but contrast-enhanced chest CT did not reveal any abnormalities. Bone marrow aspiration did not detect any infiltrations of lymphoid cells but was suggestive of hemophagocytic syndrome. After that, a new cerebral infarction occurred. Based on the course, intravascular lymphoma, which causes microvascular occlusions in various organs, was considered probable. Prednisolone was administered at a dose of 60 mg daily and skin biopsy was scheduled. However, the patient experienced a sudden deterioration and died. In autopsy, immunostain with CD20 showed that the arteriolae, capillaries, and venulae of thoracic and abdominal organs were filled with cells of large B-cell lymphoma. The presence of similar cerebrovascular lesions was not confirmed, but can reasonably be speculated. Thus, the present case suggests that it is necessary to consider intravascular lymphoma when dementia rapidly progresses for unknown reasons.