Cystic meningioma: unusual imaging appearance of a common intracranial tumor

Abstract

Meningiomas are common tumors of the central nervous system that account for approximately 15% of all intracranial tumors and are the most common extra-axial neoplasm. Most meningiomas are benign, although atypical and malignant meningiomas also exist. Typical imaging characteristics include a well-circumscribed, homogeneously enhancing, extra-axial mass on both computed tomography and magnetic resonance imaging. The presence of an associated cyst is an uncommon imaging feature that may make it difficult to distinguish the tumor from a primary intra-axial glial neoplasm. The presence of peritumoral edema can also be a misleading finding. We present a case of a woman who presented with a history of multiple recent falls, decreased energy, and increased somnolence and was found to have a "cystic meningioma." Typical imaging characteristics, histologic subtypes, treatment, and prognosis are also discussed.

Figure 1

Noncontrast axial CT images demonstrate (a) considerable vasogenic edema throughout the right frontal lobe and subfalcine herniation and (b) an isodense mass overlying the right frontal lobe with significant marked vasogenic edema.

Figure 2

Axial magnetic resonance images. (a) Fluid-attenuated inversion recovery image demonstrates a hyperintense mass overlying the right frontal lobe with an adjacent cystic component and surrounding vasogenic edema. (b) T1-weighted post-gadolinium contrast image reveals avid enhancement of the extra-axial mass. The adjacent cystic component does not exhibit enhancement.

Figure 3

Intraoperative photo demonstrates a vascular extra-axial mass (∗) adherent to the dura overlying the right frontal lobe.

Figure 4

High-power-field histopathologic section demonstrates spindle-shaped cells forming fascicles and whorls with partial immunoreactivity for epithelial membrane antigen.

Figure 5

Axial T1 weighted (a) pre- and (b) post-gadolinium infusion images demonstrate a homogeneously enhancing extra-axial mass overlying the left frontal lobe typical for a meningioma. (c) Post-contrast axial CT image demonstrates an enhancing extra-axial mass in the left cerebellopontine angle (∗) consistent with a meningioma. (d) Axial CT image utilizing a bone algorithm shows associated hyperostosis along the dorsal margin of the petrous apex (arrow) at the base of the meningioma.

Figure 6

Digital subtraction angiographic images (lateral projection) from an external carotid artery injection demonstrate filling of an enlarged middle meningeal artery branch with (a) early arterial phase tumor blush (long arrow) and (b) persistent tumor blush (∗) on late venous phase images (i.e., “mother-in-law” pattern of enhancement). Notice the persistent tumor blush of an additional smaller meningioma (short arrow) in this patient with neurofibromatosis type 2.