T1 axial post gad T2 axial FIR axial

Diagnosis: Grade 3 multifocal or multicentric astrocytoma

High grade astrocytomas (grade 3 or anaplastic and grade 4 or glioblastoma multiforme) typically present in an older age group from 40 to 60. The less aggressive variety are grade 1 and 2 astrocytomas which present in a younger age group. High grade astrocytomas are usually fatal within 2 years and typically present as enhancing deep white matter lesions with mass effect. Multifocal astrocytomas are those with no microscopic connection, while multicentric refers to lesions which are connected.

Metastases are a consideration particularly due to the fact that there is more than one lesion. However, metastases tend to be more enhancing and focal in their appearance than seen here. There is usually a history of a primary neoplasm elsewhere. Herpes Simplex encephalitis typically presents with abnormal signal in the subfrontal, temporal, or insular regions. There is usually some degree of gyral enhancement particularly in the later stages of the disease. There is often mass effect along with the signal abnormality. The finding here that goes against HSV encephalitis is the enhancement in the midbrain and signal change in the contralateral pons. HSV patients tend to be toxic with altered mental status, high fevers, and seizures. The finding of a multifocal signal abnormality with mass effect and enhancement in a patient who is not toxic and with no known primary neoplasm suggests the diagnosis of multifocal or multicentric astrocytoma. Related Cases

Multiple astrocytomas Brainstem astrocytoma Multiple astrocytomas