Anterior temporal lobe perivascular spaces, also known as opercular perivascular spaces, are special variants of tumefactive perivascular spaces, which can mimic cystic tumors with surrounding edema.
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Epidemiology
A predilection for women has been reported 1. Age range is wide, from 24 to 86 years old reported 1.
Clinical presentation
As is the case with perivascular spaces elsewhere, no symptoms directly attributable to the lesion are usually identified 1.
Pathology
The origin of these lesions is uncertain and they may be unrelated to other perivascular spaces. A number of possible etiologies have been proposed including occlusion of small communicating channels by the vascular loop resulting in accumulation of fluid and/or as a result of abnormal CSF dynamics 3.
Location
Importantly, these lesions are not exclusively found in the anterior temporal lobe, but rather also in the frontal operculum, thus the proposed alternative name of opercular perivascular spaces 3.
Radiographic features
MRI
Unlike tumefactive perivascular spaces elsewhere within the brain, anterior temporal lobe perivascular spaces often have surrounding edema (~80%) which can range from mild to extensive 1. Additionally, they are usually associated with a branch of the middle cerebral artery and a focal region of cortical thinning or absence (~90%) 1. Otherwise, they have similar appearances to perivascular spaces elsewhere: internal CSF signal on all sequences and no enhancement 1,2.
The size of the cyst invariably remains stable. Surrounding edema, however, can change over time in a small percentage of cases, either increasing or decreasing in conspicuity 1,2.
Treatment and prognosis
No treatment is required provided that they are recognized as perivascular spaces. Change in the size of the cyst or presence of enhancement should make one doubt the diagnosis. In some instances, particularly those with increasing edema, a biopsy may be required to exclude a tumor. Care must be taken, however, as reactive astrocytosis can be mistaken for a glial tumor leading to further surgery and treatment, especially as the tissue will naturally enough be IDH wildtype.