PAX5 and Large vessel vasculitis: CT head: unremarkable; MRI brain: bilateral embolic infarcts; serial brain MRIs demonstrated evolving multiage infarctions that were atypical of embolic etiology; cerebral angiogram: unremarkable for large vessel vasculitis; EEG: unremarkable; whole-body PET scan: hypermetabolic 4-mm cervical lymph node suspicious for nodal metastasis; brain biopsy: focal dilated vessels containing abnormal lymphoid cells, with Immunostaining positivity of PAX5 and CD20 consistent with IVL