Glioblastoma mimicking herpes simplex encephalitis

Abstract

We report a case of 70-year-old man with glioblastoma presenting as acute encephalitic illness. The patient exhibited sudden onset of cognitive impairment and headache for 2 days. Initial brain MRI showed left temporal lobe hyperintensity, and cerebrospinal fluid cytology revealed a mild pleocytosis. The patient had initially improved after medical treatment with a presumptive diagnosis of herpes simplex encephalitis (HSE). After 8 months, the patient complained of recurrent seizures. A follow-up brain MRI revealed marked increases in size and surrounding perilesional edema in the left temporal lesion on T2-weighted images and a new contrast-enhancing lesion on gadolinium-enhanced T1-weighted images. Stereotactic brain biopsy revealed a glioblastoma. The atypical encephalitic presentation of glioblastoma should be considered if definitive evidence for the diagnosis of HSE cannot be obtained.

Keywords: Glioblastoma; Herpes simplex encephalitis.

Fig. 1

Brain MRI and Fluorine-18 fluorodeoxyglucose positron emission tomography (¹⁸F-FDG PET) scan at admission. Axial T2-weighted image shows a hyperintense lesion with mild swelling in the left medial temporal lobe (A, B and C). Gadolinium-enhanced T1-weighted image shows normal findings (D and E). Transaxial PET scan reveals a well-defined region of increased uptake of ¹⁸F-FDG in the left medial temporal lobe (F).

Fig. 2

Brain MRI and pathologic examination at an 8-month follow-up. Axial T2-weighted image shows an extensively diffuse hyperintense lesion with central necrosis, marked perilesional edema in the left temporal lobe and compression of the left cerebral peduncle (A, B and C). Gadolinium-enhanced T1-weighted image shows an irregular peripheral rim-enhancement with central necrosis and surrounding perilesional edema (D and E). Pathologic examination reveals an increased cellularity, tumor necrosis, and endothelial cell proliferation (hematoxylin and eosin stain, ×100) (F).