[A case of intravascular large B-cell lymphoma that presented with recurrent multiple cerebral infarctions and followed an indolent course].

A 66-year-old woman presented with vertigo and deafness. Diffusion-weighted magnetic resonance imaging of the head showed multiple cerebral infarctions involving several blood vessel regions. A diagnosis of cardiogenic embolism was made, and anticoagulation therapy was begun. The woman had no additional symptoms until suddenly developing left hemiparesis one year later. She was again found to have multiple cerebral infarctions. The hemiparesis gradually improved, but ataxic gait and apraxia appeared and progressed over two weeks. Holter ECG, carotid ultrasound, and transthoracic/transesophageal echocardiography revealed no evidence of cardiogenic embolism. However, serum lactate dehydrogenase (LDH) and soluble interleukin-2 receptor (sIL2R) levels were elevated (LDH, 782 IU/l; sIL2R, 1,396 IU/ml), which suggested malignant lymphoma. Contrast chest/abdominal CT scan and gallium-67 scintigraphy revealed no evident lesions; however, random skin biopsy and open brain biopsy showed that blood vessels were infiltrated by CD20-positive atypical lymphocytes. These findings were consistent with intravascular large B-cell lymphoma. This type of lymphoma is known as a rapidly progressive disease with poor prognosis, but this case followed an indolent course, with a one-year interruption in disease progression.