Female, 11 years old, with history of pilocytic astrocytoma with VP shunt. Yearly follow-up exam. Heterogeneous T2 hyperintense, partially cystic signal characteristics are evident within the right basal ganglia and thalamus, right hypothalamus, and to a lesser degree the left hypothalamus. Pathologic signal extends inferiorly to involve the medial right temporal lobe structures, and in particular, the right amygdala is T2 hyperintense and perhaps mildly thickened relative to the left.The region of abnormal parenchyma involving the right basal ganglia and thalamus is surrounded by patchy intrinsic T1 hyperintensity. A focus of intrinsic T1 hyperintensity is also seen within the right cerebral peduncle. No clear evidence of any true enhancement is seen above and beyond this intrinsic T1 signal.A right parietal approach ventricular catheter is in place and appears to terminate within the body of the right lateral ventricle. The right lateral ventricle is of normal caliber while the left is collapsed. No evidence of any ventricular dilatation is seen.There is no evidence of any significant parenchymal edema or mass effect. The abnormal right basal ganglia/thalamic tissue shows patchy susceptibility effect likely representing chronic blood product. No acute intracranial hemorrhage or other abnormal collections are suspected. A cystic pineal lesion which measures approximately 1 cm in diameter is likely benign and incidental.
Patchy abnormal signal with evidence of hemosiderin staining and cystic tissue is seen involving predominantly the right basal ganglia and thalamus. Signal abnormality, however, does extend inferiorly into the medial temporal lobe. Without prior examinations for comparison, interpretation of these findings is somewhat limited though they may very well represent the sequelae of a treated or involuted pilocytic astrocytoma as indicated in the clinical history.If prior examinations can be made available, we will be happy to perform a comparison and addend this report.