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| T1 post-gad | T1 post-gad | FIR |
Diagnosis: Grade 3 astrocytoma
Grade 3 astrocytomas are otherwise known as anaplastic astrocytomas. They along with glioblastomas (grade 4) usually present between the ages of 40 and 60 in the white matter of the cerebral hemispheres, although they may be seen in the posterior fossa. Symptoms may include headache, seizures or focal neurologic deficit. On imaging, high grade astrocytomas usually present as deep white matter lesions with a large amount of surrounding vasogenic edema with mass effect and some enhancement which may be ring enhancing from the central necrosis. Little or no enhancement is possible, but atypical. Small foci of hemorrhage may be present but gross hemorrhage is unusual. Calcification in astrocytomas is an uncommon finding. In this patient there is abnormal signal within the pons accompanying the mass within the fourth ventricle. This suggests either a pontine tegmental mass with an exophytic component or a fourth ventricular mass which has invaded the pontine tegmentum. Ependymoma may produce this appearance; however, this lesion enhances much less than the usual ependymoma. In an older patient, metastasis is always a consideration. However, metastases are multiple in 80% of cases and usually enhance more than this. Hemangioblastoma may occur sporadically and present as a posterior fossa mass without von Hippel Lindau disease. 40% of hemangioblastomas are solid and they have intense enhancement due to their high vascularity. The rest are cystic with an enhancing nodule. In this case, the lesion is mostly in the 4th ventricle, exophytic from the pons. Related Cases
