Imaging Features and Pathological Correlation in Mixed Microcystic and Angiomatous Meningioma: A Case Report

Abstract

Meningiomas are the most common intracranial tumors. However, microcystic and angiomatous meningiomas are very rare subtypes that present unusual imaging findings. Hence, radiological diagnosis of these tumors can be challenging. We herein describe a case of mixed angiomatous and microcystic meningioma in an 81-year-old male. MRI revealed an extra-axial mass with high T2 signal intensity, measuring 1.5 cm in diameter, with multiple tiny intralesional cysts and entrapped peritumoral cyst formation. After tumor resection, a histopathological diagnosis of mixed angiomatous and microcystic meningioma was made.

Keywords: Angiomatous Meningioma; Magnetic Resonance Imaging; Meningioma; Microcystic Meningioma.

Fig. 1. An 81-year-old male with mixed angiomatous and microcystic meningioma in the left frontal region.

A. T2-weighted axial MR images show a well-defined, predominantly cystic, partially solid mass with mild peritumoral brain edema. The mass measures 6.0 cm × 5.7 cm × 4.2 cm in the left frontal lobe and its large, peripherally located cystic portion shows a slightly higher SI than the cerebrospinal fluid on fluid attenuated inversion recovery sequence (not shown here), with invagination into the brain parenchyma like a mushroom. The wall of the mass shows a thin rim with low SI (red arrow). The 1.5 cm × 1.4 cm × 1.3 cm, intracystic, solid mass (yellow arrow) shows a solid portion with high T2 SI and small intratumoral cysts. Surgical inspection identified the peripheral cystic portion to be an entrapped peritumoral cyst formation with a reactive fibrous membrane. Note that the signal void (arrowhead) by the left anterior cerebral artery is located between the cerebral cortex and the mass. When the signal void is traced, it turned out to be a displaced left anterior cerebral artery. A more comprehensive retrospective review of this information indicated that the tumor is completely extra-axial, with broad attachment to the falx cerebri. B. Post-contrast, T1-weighted, axial, coronal, and sagittal images show strong enhancement of intracystic tumor solid portion, while the small cystic portions, with a bubbly or reticular appearance (arrows), show no such enhancement. The large cyst wall with several thin, linear enhancements (arrowheads) was later identified as a fibrous membrane. C. An angiomatous meningioma area shows numerous densely packed blood vessels admixed with meningothelial cells wrapped around the blood vessels (H&E stain, × 100). D. Vessels are immunostained for CD34 (× 100). E. A microcystic meningioma area shows a loosely reticular, lace-like appearance with numerous extracellular cystic spaces (H&E stain, × 200). SI = signal intensity, H&E = hematoxylin & eosin