Anaplastic astrocytoma mimicking herpes simplex encephalitis in 13-year old girl

Abstract

Astrocytoma is the most common childhood brain tumor. Anaplastic astrocytoma (AA) are high grade gliomas (HGG), found very rarely in pediatric patients. AA mainly results from a dedifferentiation of a low grade astrocytoma. Clinical features of supra-tentorial tumors vary according to their anatomic location, biologic aggressiveness and age of the patient. They can be either completely asymptomatic or present with signs of raised intracranial pressure, seizures (about 40% of cases), behavior changes, speech disorders, declining school performance, or hemiparesis. There have been published adult cases of brain tumor misdiagnosed as viral encephalitis. Due to variety of clinical presentations, diagnosis of AA can be challenging. Here we report a case of a 13 year old girl who presented with clinical features suggestive of viral encephalitis, such as fever, headache, dizziness, and first seizure with postictal sleep and prolonged drowsiness. However, her brain MRI findings were consistent with long standing mass effect from the underlying intracranial contents and that coupled with her history of unusual taste led to further investigations and the diagnosis of the AA. In retrospect, this presentation could have been a temporal epileptic aura. High grade astrocytomas are particularly difficult to treat with a two-year survival rates range from 10% to 30%. The treatment is multimodal with gross total surgical resection of the tumor, followed by radiotherapy with or without nitrosourea-containing chemotherapy regimen. Recent promising results seen with the use of temozolamide in adults has not been yet demonstrated in the pediatric patients. The extent of tumor resection remains the most significant indicator of survival and early recognition of this tumor is essential. This case report emphasizes the fact that mass lesions in the temporal lobe, including high-grade astrocytoma, should be considered in the differential diagnosis of suspected herpes simplex encephalitis, especially those not responding to therapy. Remodeling of the calvarium adjacent to an intracranial lesion suggests a long standing process.

Keywords: Anaplastic astrocytoma; Brain tumor; HSV encephalitis; Radiodiagnosis.