Meningiomas are a diverse group of brain tumors that arise from the arachnoid layer (specifically the arachnoid cap cells) and can therefore occur in any part of the CNS with a meningeal covering.

Epidemiology

• Most common benign primary brain tumor in adults

Etiology

• Multiple meningiomas may develop in patients with neurofibromatosis type II.

Pathophysiology

Clinical features

• Mostly asymptomatic
  • Meningiomas are slow-growing tumors and, as such, they are less invasive and the body has more time to adapt to the tumor.
• General symptoms of CNS tumors (e.g., seizures and focal neurologic signs)

Diagnostics

MRI (imaging modality of choice)

• Plain MRI findings
  • Round, sharply demarcated space-occupying lesion with radiological features of an extra-axial tumor
  • Dural tail sign
  • T1: isointense or hypointense
  • T2: isointense or hyperintense
• Contrast MRI findings
  • Significant homogenous enhancement of the meningioma
    • As meningiomas grow, they often stimulate angiogenesis

Pathology

Microscopic findings

• Mesenchymal origin (arachnoid cap cells)
• Whorls of meningothelial cells (onion peel arrangement)
• Psammoma bodies Two of these whorls have a deeply basophilic acellular core, known as a psammoma body, which indicates dystrophic calcification.

Treatment