Background: Gliomatosis cerebri is a rare neoplasm in which individual neoplastic cells diffusely permeate the brain; a cohesive tumor mass may appear late in the disease course, or not at all. The diagnosis can be made either at autopsy or premortem by combining biopsy and neuroimaging findings to demonstrate involvement of more than two lobes of the brain. Extensive hemispheric white matter and corpus callosum infiltration is characteristic, with lesser spread to subcortical and cortical gray matter. Whereas this pattern of localization can be predicted to cause significant disturbances of higher function, the neurobehavioral profile of gliomatosis cerebri patients has not been well described.
Method: Three patients with gliomatosis cerebri had detailed neurobehavioral assessment, and one had neuropsychological testing early in the disease. Neuropathological investigation focused on the localization of the neoplasm, the correlation between extent of myelin and axon damage with tumor cell density, and the histogenesis of the tumor.
Results: The patient with neuropsychological testing had impaired executive function and verbal memory retrieval that reflected bifrontal and left temporal white matter tumor involvement seen on neuroimaging. In the other cases, apathy and fatigue progressed to severe dementia in association with bihemispheric white matter infiltration. Myelin and axon stains and myelin stains showed relative preservation of white matter architecture with severity of damage paralleling increased tumor cell density. Immunostaining for TP53 was found in a high percentage of tumor nuclei in two of three cases, suggesting overlapping features between gliomatosis cerebri and diffuse astrocytomas.
Conclusions: Subtle cognitive and emotional alterations antedate the florid dementia that develops later in the course of gliomatosis cerebri. Clinical, neuroimaging, and neuropathological data suggest that white matter is damaged directly by the tumor and its associated mild edema, although infiltration of subcortical and cortical gray matter also occurs to a variable extent. Strong TP53 immunostaining in gliomatosis cerebri suggests a commonality with diffuse fibrillary astrocytomas that also often show TP53 staining. Gliomatosis cerebri can be considered a cause of white matter dementia resulting from preferential neoplastic disruption of white matter tracts.