Meningioma (Brain)

Diagnosis Definition

• Meningioma is the most common primary brain tumor; it arises from the meninges, grows slowly, and is often found incidentally on CT or MR imaging
• 95% of Meningiomas are benign and 5-15% are multiple, especially in patients with neurofibromatosis type 2
• The incidence is greater in women and in patients over age 60
• Meningiomas can become quite large and result in bony changes of hyperostosis, permeative destructive changes, or erosion

Imaging Findings

• Meningiomas typically appear as lobular, extra axial masses with well-circumscribed margins
• They typically have a broad-based dural attachment and, if sufficiently large, inward displacement of the cortical grey matter
• On MRI, meningiomas are typically isointense to slightly hypointense relative to grey matter on the T1-weighted sequence and isointense to slightly hyperintense relative to grey matter on T2
• Meningiomas typically demonstrate avid, homogeneous contrast enhancement

KEY IMAGES

Pearls

• The differential diagnosis of intracranial meningioma includes esthesioneuroblastoma, sinonasal undifferentiated tumor, osteoma, metastasis, hemangioma, and fibrous dysplasia
• Meningiomas located at the skull base have the potential to encase the carotid arteries and cause luminal narrowing; however, cerebrovascular insufficiency is exceedingly rare
• Extra axial location is suggested by the presence of a CSF cleft between the tumor and the underlying brain cortex
• Calcification is typically best demonstrated on CT, with variable reported rates of occurrence

References

1. Buetow MP, Buetow PC, Smirniotopoulos JG. Typical, atypical, and misleading features in meningioma. RadioGraphics 1991; 11(6):1087–1106
2. Watts J, Box G, Galvin A, et al. Magnetic resonance imaging of meningiomas: a pictorial review Insights Imaging 2014; 5(1):113–122