Subcortical cystic lesions within the anterior superior temporal gyrus: a newly recognized characteristic location for dilated perivascular spaces

Abstract

Cystic parenchymal lesions may pose an important diagnostic challenge, particularly when encountered in unexpected locations. Dilated perivascular spaces, which may mimic cystic neoplasms, are known to occur in the inferior basal ganglia and mesencephalothalamic regions; a focal preference within the subcortical white matter has not been reported. This series describes 15 cases of patients with cystic lesions within the subcortical white matter of the anterior superior temporal lobe, which followed a CSF signal; were located adjacent to a subarachnoid space; demonstrated variable surrounding signal change; and, in those that were followed up, showed stability. Pathology study results obtained in 1 patient demonstrated chronic gliosis surrounding innumerable dilated perivascular spaces. These findings suggest that dilated perivascular spaces may exhibit a regional preference for the subcortical white matter of the anterior superior temporal lobe. Other features-lack of clinical symptoms, proximity to the subarachnoid space, identification of an adjacent vessel, and stability with time-may help in confidently making the prospective diagnosis of a dilated perivascular space, thereby preventing unnecessary invasive management.

Fig 1.

Selected axial FLAIR/T2 images of right-sided lesions within the anterior superior temporal gyrus as identified in case 1 (A), 2 (B), 7 (C), 8 (D), 9 (E), 10 (F), 12 (G), and 14 (H). All lesions were located adjacent to the SAS. The images illustrate the variability in the degree of surrounding signal change. Note the proximity to the adjacent middle cerebral artery and more prominent surrounding signal hyperintensity seen in case 7 (C).

Fig 2.

Selected axial FLAIR images of left-sided lesions within the anterior superior temporal gyrus as identified in case 3 (A), 4 (B), 5 (C), 6 (D), 11 (E),13 (F), and 15 (G). All lesions were located adjacent to the SAS. Again, the images illustrate the variability in the degree of surrounding signal change.

Fig 3.

Selected axial FLAIR images demonstrating the presence of a cystic lesion within the anterior temporal gyrus as identified in case 6 (A) and case 11 (B), with adjacent smaller cystic lesions, suggestive of a dominant enlarged perivascular space with adjacent smaller prominent perivascular spaces (arrows). Corresponding coronal T2 images (below) through the region of interest confirm these findings (arrows). In case 11 (B), the proximity to the adjacent middle cerebral artery is identified on the coronal T2 image.

Fig 4.

Trichrome stain (A) demonstrates the presence of an enlarged perivascular space (white arrow, glia limitans; black arrow, inner pial membrane; black arrowhead, vessel lined by outer pial membrane; curved arrow, perivascular space). Multiple such lesions were seen in the surgical specimen. Glial fibrillary acidic protein stain (B) and CD68 stain (C) demonstrate reactive astrocytes (arrows in B) and perivascular microglia (arrows in C) as multiple brown-staining dots, confirming chronicity of the pathophysiologic process. Luxol fast blue stain (D) demonstrates diffuse absence of blue staining (myelin staining), indicating demyelination and gliosis in the brain parenchyma surrounding the dilated perivascular space (magnification of all slides, 20×).