[A case of pontine astrocytoma with unusual neuroimaging features].

We would like to report a rare case of pontine glioma with unusual neuroimaging features. The patient was a 3-year-old girl who suffered from chronic nausea and gait disturbance for several months. Computed tomography (CT) demonstrated ventricular dilatation, and ventricular peritoneal (VP) shunt was performed for idiopathic hydrocephalus at another hospital. Fever of unknown origin continued for a month after the VP shunt. At our hospital, cerebrospinal fluid examination showed bacterial meningitis, and it was assumed that shunt infection lead to shunt failure. Magnetic resonance imaging (MRI) revealed hydrocephalus and pontine swelling, and serial MRI suggested brainstem tumor extending to the bilateral thalamus. The patient underwent stereotactic biopsy of the left thalamic tumor, under general anesthesia, and the histological diagnosis was anaplastic astrocytoma. Diffuse pontine glioma rarely increases without cranial nerve deficits. In the present case, pontine glioma extended to the bilateral thalamus symmetrically. It was difficult to diagnose the presented lesion as pontine glioma in the early period because of its unusual neuroimaging.