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| T1 sagittal pre gad | T1 axial post gad | T2 axial |
Diagnosis: Brain stem astrocytoma
Brain stem astrocytomas represent approximately 1/4 of all infratentorial neoplasms. Peak incidence is between 3 and 10 years of age with boys and girls being affected equally often presenting with cranial nerve findings. Hydrocephalus is uncommon since most become clinically apparent prior to obstruction of the fourth ventricle. Calcification and hemorrhage are unusual and enhancement is variable. Encephalitis could have this appearance, but that would be much less likely. Ependymoma is not in the differential since it would typically be within the fourth ventricle and enhance heterogeneously. Other infratentorial pediatric neoplasms include juvenile pilocytic astrocytoma, hemangioblastoma and medulloblastoma. JPAs and hemangioblastomas often present as cystic masses in the cerebellar hemisphere with an enhancing mural nodule, however, they may be solid. JPAs also occur around the 3rd or 4th ventricle. Medulloblastoma is an intensely enhancing mass usually in the midline but may present in the cerebellar hemisphere. Related Cases
