Anaplastic meningioma is a rare and aggressive brain tumor that originates from the meninges, the protective membranes surrounding the brain and spinal cord. While most meningiomas are benign, anaplastic meningioma is malignant. It is classified as a high-grade, World Health Organization (WHO) Grade III tumor, indicating its aggressive behavior. This type accounts for a small percentage of all meningiomas, typically 1% to 4% of cases.
What is Anaplastic Meningioma?
Anaplastic meningioma is designated as a World Health Organization (WHO) Grade III tumor, signifying its aggressive and cancerous characteristics. This classification distinguishes it from lower-grade meningiomas, which are typically benign (Grade I) or atypical (Grade II). Anaplastic meningiomas exhibit rapid growth rates and a higher likelihood of recurrence following treatment.
Under microscopic examination, anaplastic meningiomas display specific cellular features that denote their aggressive nature. These include increased mitotic activity, meaning a higher number of cells are actively dividing. The cells often show nuclear pleomorphism, indicating varied sizes and shapes of cell nuclei, and may exhibit frank anaplasia, where there is a loss of normal meningothelial differentiation. Additionally, areas of necrosis, or cell death, are frequently observed within these tumors. This aggressive cellular behavior contributes to their propensity for local invasion into surrounding brain tissue.
Recognizing and Diagnosing Anaplastic Meningioma
Anaplastic meningiomas can manifest through various symptoms, which vary depending on the tumor’s size and location. Common symptoms may include persistent headaches and seizures. Individuals might also experience changes in vision or neurological deficits like weakness, numbness, or speech difficulties.
The diagnostic process typically begins with imaging techniques. Magnetic Resonance Imaging (MRI) and Computed Tomography (CT) scans are used to detect the presence of a mass and assess its characteristics. While imaging can suggest a meningioma, a definitive diagnosis and accurate grading require a tissue sample. Therefore, a surgical biopsy is performed, followed by a thorough pathological examination of the tissue by a neuropathologist. This microscopic analysis confirms the tumor type and assigns its WHO grade, which is fundamental for guiding subsequent treatment decisions.
Treatment Strategies
The management of anaplastic meningioma typically involves a multidisciplinary team of specialists. Surgical resection is the cornerstone of treatment, with the objective being the maximal safe removal of the tumor. Achieving a gross total resection, meaning the complete removal of all visible tumor tissue, is often associated with better outcomes, though this is not always feasible due to the tumor’s location or its invasion into surrounding structures.
Following surgery, radiation therapy is a standard adjuvant treatment for Grade III anaplastic meningiomas. It targets any remaining tumor cells and reduces the likelihood of recurrence. This can involve external beam radiation therapy. For tumors that are unresectable or for recurrent cases, radiation therapy may serve as the primary treatment modality. Systemic therapies, such as chemotherapy and targeted therapies, are generally reserved for specific situations, like recurrent disease or when other treatments are no longer effective. These therapies aim to control tumor growth.
Outlook and Ongoing Care
The prognosis for individuals diagnosed with anaplastic meningioma is generally less favorable compared to those with lower-grade meningiomas, due to its aggressive nature and higher likelihood of recurrence. Recurrence rates for completely resected Grade III meningiomas can be around 63% within five years, with all recurrences typically observed within ten years.
Ongoing surveillance is a fundamental component of post-treatment care, involving regular MRI scans to detect any signs of tumor recurrence. For WHO Grade III meningiomas, MRI scans are often recommended every four months for the first two years after surgery, followed by scans every six months indefinitely. Supportive care and symptom management are also important to enhance the patient’s quality of life. This includes addressing neurological deficits, managing pain, and providing psychological support for patients and their families.