Gliomatosis Cerebri Mimicking Viral Encephalitis – A Case Report

We present a case of a patient with a radiological diagnosis of gliomatosis cerebri whose clinical presentation mimicked that of viral encephalitis. A 69-year-old female presented with a few days history of confusion, headache and fever. Examination revealed mild extensor weakness in the left upper and lower limb. CSF showed a mild pleocytosis; gram stain, bacterial and viral cultures as well as HSV PCR were negative. CT brain showed diffuse right hemispheric oedema with a focal enhancement in the temporal lobe, which was also demonstrated on MRI brain. Aciclovir and dexamethasone were started for presumed viral encephalitis. After 8 days of treatment, the patient's symptoms improved and she was discharged. One week later, the patient was more confused with new left sided hemianopia. Repeat MRI brain revealed progression of the diffuse right-sided oedema, extending into the corpus callosum and cerebellum. Following discussion with a specialist neurooncology centre, we were advised that the images were indicative of extensive Gliomatosis Cerebri. Unfortunately, the patient died of pneumonia before tissue diagnosis was obtained. GC is a rare form of infiltrative glioma involving three or more lobes of the CNS. It has a varying clinical presentation and there are frequent case reports of GC mimicking alternative diagnoses. GC has been reported to mimic viral encephalitis in only one previous adult case.