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. 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.
Enhancement is generally minimally or absent in small lesions.
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