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A 5-year-old woman presented with bilateral papilledema, headache and vomiting resulting from increased intracranial pressure.
Sagittal T1-weighted MR image (SE 500/20) shows a 1.6 x 2 cm bulbous-tectal mass (white arrow) causing obstruction of the Sylvian aqueduct (black arrow) and hydrocephalus.
Axial T1-weighted MR image (SE 500/20) shows enlargement and asymmetry of the quadrigeminal plate (arrow). Lateral (arrows) and third (*) ventricles are dilated. The small lesion (arrow) has low signal intensity on T1-weighted images and it doesn't enhance after Gd-DTPA administration.
Axial PD and T2-weighted MR images (SE 2500/40/90) shows the mass (arrow) to be hyperintense compared to surrounding brain tissue. Irregular hyperintensity in the periventricular white matter (arrows) on PD and T2-weighted MR images (SE 2500/40/90) suggest diagnostic of transependymal CSF resorption.
Diagnosis
Tectal glioma
Differential Diagnosis
A diverse group of lesions can involve the tectal region of the brain. Intrinsic neoplastic tectal lesions (quadrigeminal plate lesions) includes tectal glioma and lymphoma. The former appears as a mass that enlarge the tectum and shows a low signal intensity on T1-weighted images and high signal intensity on T2-weighted images. Enhancement is generally minimally or absent in small lesions. These tumors originating in the quadrigeminal plate may completely obliterate the aqueduct causing hydrocephalus. A solitary, deep intraaxial mass with signal similar to that of brain that shows intense and uniform enhancement and minimal edema should suggest diagnosis of lymphoma. Hydrocephalus due to an aqueductal lesion may cause the tectum to appear short and thick. Distinction of compressed tectum from tectal astrocytoma can be difficult, particularly because astrocytomas in this region are generally low grade and small lesions often do not enhance. Pineal cell tumors (pineoblastoma and pineocytoma) and other common pineal region tumors are also an important cause of tectal compression. Very rarely gliomas develop from astrocytes within the pineal gland itself. Commonly these tumors arise from brain parenchyma, such as the quadrigeminal plate, and grow into the pineal region secondarily.
Discussion
Tectal gliomas are usually low-grade astrocytomas that enlarge the tectum and may completely obliterate the aqueduct causing hydrocephalus. In this case patients typically present with neurologic symptoms resulting from increased intracranial pressure. MRI depicts these lesions as a bulbous mass originating in the quadrigeminal plate that shows a low signal intensity on T1-weighted images and high signal intensity on T2-weighted images. Enhancement is generally minimally or absent in small lesions.
References
1. Atlas SW. Magnetic Resonance Imaging of the brain and spine. 1st ed. New York, Raven Press, 1991.
2. Barkovich AJ. Pediatric neuroimaging. 2nd ed. New York, Raven Press, 1995.
3. Friedman DP. Extrapineal abnormalities of the tectal region: MR Imaging findings. AJR 1992; 159: 859-866
Gianvincenzo Sparacia M.D. (radpa@mbox.unipa.it)
University of Palermo, Institute of Radiology "P. Cignolini"
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T1-weighted MRI
PD and T2-weighted
MRI
T1-weighted MRI
post Gd-DTPA
