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case_images: A-B) Preoperative MRI. T1-weighted sagittal and T2-weighted axial images demonstrating the tumour mass with a cystic component and extension into the floor of the fourth ventricle and to the supravermian cistern. Partial obstruction of the fourth ventricle and secondary obstructive hydrocephalus is also observed. C-D) Two-year postoperative MRI. No apparent residual tumour is shown at T1-weighted sagittal and T2-weighted axial images
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case_images: Postcontrast images revealed minimal enhancement (Fig. 1A and 1B). MRI two years after surgery revealed no residual tumour (Fig. 1C and 1D).
case_images: Microscopic features of the rosette-forming glioneuronal tumour. A) Histological features of the tumour showing both a neurocytic and an astrocytic component. Neurocytic rosettes are formed by the neurocytic components. B) The eosinophilic core at the centre of the neurocytic rosettes displays strong positive staining with synaptophysin. C) The astrocytic components of the tumour showed that the tumour cells had bipolar and spindle processes with positive immunostaining of GFAP. D) The MIB-1 labelling index was about 5-7%. Original magnifications 400x
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case_images: Based on these features, a diagnosis of RGNT grade I was made (Fig. 2).
case_images: A-B) MRI scans 48 months after the initial procedure. T1-weighted sagittal and T1-weighted axial contrast enhanced images reveal a nodular lesion close to the roof of the fourth ventricle. C-D) T1-weighted sagittal and T2-weighted axial MRI images two years after radiosurgery show stabilisation of the lesions
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case_images: Control MRI after four years revealed a nodular enhancing 10-mm lesion with increased angiogenesis close to the roof of the fourth ventricle, without perilesional oedema, and a second lesion 13 mm in size, close to the posterior edge of the quadrigeminal lamina (Fig. 3A and 3B).
case_images: Treatment planning for gamma knife radiosurgery. A) Sagittal view. B) Axial view. C) Coronal view
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case_images: The tissue volume included in the isodose area was 5.32 cc (Fig. 4).