An important point of view in this report are the symmetrical findings in the temporal lobes in combination with involvement of the cingulate gyrus which initially were misdiagnosed as limbic encephalitis. The prognosis of IML is poor with a median survival time of only 6 months after symptom onset. The key microscopic feature of IML is the filling of lumina of small and medium-sized vessels with large atypical lymphoid cells. These cells possess predominantly round nuclei, vesicular chromatin and prominent nucleoli.
Mitotic figures are common.
Immunohistochemically, these cells are positive for leukocyte common antigen and usually B cell markers, but a few cases of T cell origin have been described. The blood vessels are closed and sometimes thrombosed by tumor cells leading to circulation disturbances resulting in multiple, ischemic microinfarctions as well as small parenchymal hemorrhages. Consequently, brain biopsy is recommended as the preferable way to establish this diagnosis. In conclusion, in a case of dementia, seizures and infarct-like lesions by MRI, the diagnosis of an intravascular malignant lymphomatosis should be considered. Neurologic manifestations of intravascular lymphomatosis.