T1 axial post gad FIR Axial T2 axial

Diagnosis: Grade 3 multicentric or multifocal astrocytoma.

High grade lesions (III, IV) represent approximately 1/3 of all astrocytomas. Patients typically present with a focal neurologic deficit or seizures between the ages of 40 and 60. They usually occur in the white matter of the cerebral hemispheres and if high grade, typically show some enhancement. Mass affect and vasogenic edema are the rule. Small hemorrhages may be seen, but larger hemorrhages are unusual. Astrocytomas typically do not calcify and are unusual in the posterior fossa. Multicentric astrocytomas are defined as multiple lesions with no microscopic connection. Multifocal astrocytomas are those which appear distant on imaging but are connected microscopically. Gliomatosis cerebri refers to a unique type of astrocytoma usually seen in children in which there is diffuse infiltration of the white matter without enhancement or mass effect. Metastases may look like this; however, they tend to be more focal lesions at the gray white junction and should enhance. Likewise, lymphoma shows intense homogeneous enhancement. Acute demyelination can present as a mass lesion simulating neoplasm which may, or may not enhance and should be in the differential.

The finding of two non-enhancing mass lesions in a young patient with no history of a primary malignancy is most compatible with multiple low grade astrocytomas or less likely acute demyelination. The fact that they do not enhance makes the diagnosis of a higher grade tumor less likely. Related Cases

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