Gliomatosis cerebri with blindness mimicking herpes simplex encephalitis: a case report with literature review

Abstract Background Gliomatosis cerebri (GC) is a rare diffuse infiltrative growth pattern of gliomas presenting with unspecified clinical manifestations. Herpes simplex encephalitis (HSE) is a central nervous system (CNS) viral infection, usually involving temporal lobes, that can lead to acute or sub-acute cerebral dysfunction. Differentiating these entities is necessary for patients with misleading presentations and imaging findings. To the best of our knowledge, this is the first case of glioma mimicking herpes encephalitis, which has complicated by blindness. Case Presentation The patient was a 35 years-old male in a drug rehabilitation center for heroin addiction. He presented with a headache, a single episode of seizure, and a two-month history of bilateral decrease in visual acuity, which had acutely worsened. Magnetic resonance imaging (MRI) and computed tomography (CT) showed bilateral temporal lobe involvement, which when combined with the patient's demographic and history, led to empirical treatment for herpes simplex encephalitis being commenced. Unfortunately, no improvement in visual acuity was detected following this treatment. Ophthalmological studies showed bilateral papilledema, absence of visual evoked potential, and thickening of the retinal nerve fiber layer. Due to the atypical clinical presentation, normal laboratory data, and suspicious MRI findings, further investigation with magnetic resonance spectroscopy (MRS) was performed. Results showed a greatly increased ratio of choline to creatinine or N-acetyl aspartate (NAA), suggesting a possible neoplastic nature of the disease. Subsequently, the patient was referred for a brain tissue biopsy with a suspicion of malignancy. The pathology results revealed adult-type diffuse glioma with isocitrate dehydrogenase (IDH) mutation. Conclusion When presented with a young patient displaying acute or sub-acute neurological symptoms and bilateral temporal lobe involvement on MRI, it is common for clinicians to presume HSE or another viral encephalitis as the primary differential diagnosis. However, as demonstrated in this study, neoplastic lesions such as adult-type diffuse glioma must be considered, especially when the clinical and imaging findings are not completely typical for HSE.