Specific Imaging Findings

The main feature of gliomatosis cerebri (GC) is diffuse infiltration with involvement of three or more contiguous cerebral lobes with preserved architecture. The tumor is of low density by CT and may result in thickening of the white matter particularly the corpus callosum. Enhancement on CT and hemorrhage are rare. CT may occasionally be normal and MR is the imaging method of choice. The tumor is T1 hypointense and bright on T2-weighted sequences. The cortex is characteristically involved and brainstem may be affected. Contrast enhancement is rare and may be patchy in distribution. MR spectroscopic patterns vary with zones showing normal or even low choline, low n-acetyl aspartate (NAA), along with high myo-inositol and, possibly, creatine. Other zones may show increased choline levels. Perfusion studies show either normal or slightly decreased cerebral blood volume. Diffusion within the lesion is usually increased and DTI studies may show preservation of directionality but decreased fractional anisotropy. Subpial extension of GC is very rare.

Pertinent Clinical Information

This is a tumor of adults with most cases found between 40 and 50 years of age, but it may occur at any age. The presentation is nonspecific and includes long tract symptoms, dementia, headaches (generally due to underlying hydrocephalus) and seizures (implying infiltration of the cerebral cortex). Brainstem involvement may result in multiple cranial nerve deficits and corpus callosum infiltration may lead to personality changes. It is a rare process whose exact incidence is not known and the diagnosis is frequently missed initially.