Intravascular Large B Cell Lymphoma as a Cause of Multifocal Cryptogenic Stroke

The patient was a 66-year-old female with a history of left-sided breast cancer with prior lumpectomy and radiation, thyroid cancer status post-thyroidectomy who presented to the emergency department for difficulty finding words. She had unremarkable findings on computed tomography (CT) brain and electroencephalogram (EEG) testing. Three months later, she developed bilateral lower extremity weakness and was admitted to a local hospital. Bilateral embolic strokes were discovered on brain magnetic resonance imaging (MRI). Carotid ultrasound and transesophageal echocardiography were unremarkable, and a lumbar puncture (LP) demonstrated an elevated cerebrospinal fluid protein of 170 mg/dL. She was started on apixaban and transferred to an acute rehabilitation unit where she developed new urinary incontinence and bilateral lower extremity paralysis. The patient was readmitted, and MRI on the brain demonstrated evolving infarctions in the left frontal lobe. Her antinuclear antibody titer was 1:160, which raised concern for an autoimmune etiology. Intravenous immunoglobulin and methylprednisolone were administered daily with 4 sessions of plasmapheresis, resulting in mild improvement in bilateral plantar flexion. The patient was discharged on prednisone 30 mg twice daily. Two weeks later, she developed progressive right upper extremity weakness. MRI on the brain demonstrated an increase in the size, number, and extent of infarctions, and the patient was transferred to a tertiary referral center. Labs were notable for elevated inflammatory markers: lactate dehydrogenase (LD) 458, C-reactive protein 5.4, and erythrocyte sedimentation rate (ESR) 79. Cerebral angiogram did not show evidence of large vessel vasculitis, and dilated retinal examination did not demonstrate small vessel vasculitis. Whole-body positron emission tomography/CT revealed a hypermetabolic 4-mm cervical lymph node suspicious for nodal metastasis. Serial brain MRIs demonstrated evolving multiage infarctions that were atypical of an embolic etiology (Figure). Following discussion with the patient and her family, a brain biopsy was performed revealing focal dilated vessels containing abnormal lymphoid cells. Immunostaining demonstrated PAX5 and CD20 positivity consistent with intravascular large B-cell lymphoma (IVLBCL) (Figure). The patient was referred to oncology for initiation of rituximab, dexamethasone, cytarabine, cisplatin, and intrathecal methotrexate.