An 87-year-old woman presented with a 3-month history of fever, edema of the lower legs, and gait disturbance. A laboratory examination revealed high serum levels of myeloperoxidase-specific antineutrophil cytoplasmic antibody (MPO-ANCA). Although microscopic polyangiitis was initially suspected and treated, the patient subsequently developed transient hemiparesis and disturbed consciousness. Brain magnetic resonance imaging/angiography revealed infarct-like lesions, pachymeningeal involvement, and diffuse cerebral vasoconstriction. A random skin biopsy confirmed the histological diagnosis of intravascular lymphoma. Diffuse cerebral vasoconstriction and a high serum MPO-ANCA level have rarely been reported in patients with intravascular lymphoma. Endothelial damage due to immune-mediated mechanisms, tumor derived factors, or the direct interaction of lymphoma cells with endothelial cells may commonly predispose patients to both cerebral vasoconstriction and the development of ANCAs.