meningioma

A meningioma is typically a slow-growing tumor arising from arachnoid cap cells of the meninges. Most are benign (World Health Organization grade 1) but some show atypia or anaplastic features (grades 2–3). They usually cause symptoms by mass effect or seizures rather than invasion of brain tissue.

Meningiomas are the most common primary intracranial tumor in adults, with a female predominance and peak incidence in middle to older age. Risk factors include prior cranial irradiation and neurofibromatosis type 2; hormonal influences are suggested since tumors commonly express progesterone receptors.

Most tumors arise along dural reflections, such as the falx, skull base, or convexities. Histology subtypes include meningothelial, fibrous, transitional, and psammomatous, with psammoma bodies common in psammomatous meningiomas. Grading: grade 1 most; grade 2 atypical with increased mitotic activity or brain invasion; grade 3 anaplastic with high mitotic rate, aggressive behavior.

Diagnosis relies on MRI with gadolinium: extra-axial, well-circumscribed mass with dural attachment and a dural tail; CT may show calcifications. Edema can accompany larger tumors.

Management: Observation is reasonable for small, asymptomatic tumors in elderly patients. Surgical resection aiming for complete removal is standard; extent of resection is described by Simpson grade; residual disease or higher-grade tumors may require radiotherapy or stereotactic radiosurgery. Seizures are treated as needed; corticosteroids may reduce edema. Prognosis is generally favorable after complete resection, but recurrence risk rises with higher grade and incomplete resection.