Meningiomas

Meningiomas are the most common primary intracranial tumors in adults. They arise from the meninges, specifically the arachnoid cap cells, and are typically slow-growing and extra-axial. They account for about 20–30% of all primary CNS tumors and occur most often in people in their 50s to 70s; they are more common in women than men. Meningiomas can also occur in the spinal canal.

Most meningiomas are World Health Organization (WHO) grade I (benign). A minority are atypical (grade II) or anaplastic/malignant (grade III). Histology shows a whorled pattern with psammoma bodies; immunohistochemistry is usually EMA positive and vimentin positive. Genetic alterations frequently involve loss of chromosome 22q (NF2 gene), especially in sporadic tumors; radiation exposure and neurofibromatosis type 2 increase risk.

Clinical presentation depends on tumor location. Many are asymptomatic and discovered incidentally. When symptoms occur, patients may have headaches, seizures, focal neurologic deficits, or signs of raised intracranial pressure. Imaging shows an extra-axial, dural-based mass that enhances with gadolinium on MRI; a dural tail sign may be seen; calcifications are common on CT.

Management ranges from observation to intervention. Small, asymptomatic tumors may be monitored. Surgical resection aims for complete removal; Simpson grade I resection reduces recurrence. For inaccessible lesions, residual disease, or higher-grade tumors, radiotherapy or stereotactic radiosurgery (e.g., Gamma Knife) can control growth. Recurrent and multiple meningiomas may require adjuvant therapy.

Prognosis is generally favorable for WHO grade I tumors after complete resection, with long-term recurrence risk influenced by extent of resection and histologic grade. Regular follow-up with MRI is recommended.