Fibrillary astrocytoma

Fibrillary astrocytoma is a type of diffuse astrocytoma, classified as a World Health Organization (WHO) grade II brain tumor. It is the most common subtype of low-grade diffuse astrocytoma and arises from astrocytes, the star-shaped glial cells that support neurons in the central nervous system. The tumor is characterized by increased cellularity of fibrillary astrocytes with mild nuclear atypia and a diffusely infiltrative growth pattern, meaning it spreads into surrounding brain tissue without a clear border. Fibrillary astrocytomas can occur in any region of the brain but are most commonly found in the cerebral hemispheres, particularly the frontal and temporal lobes. Key symptoms depend on the tumor's location and size and may include seizures (often the presenting symptom), headaches, cognitive changes, personality or behavioral alterations, focal neurological deficits such as weakness or speech difficulties, and increased intracranial pressure. Because these tumors grow slowly, symptoms may develop gradually over months to years before diagnosis. However, fibrillary astrocytomas carry a risk of malignant progression to higher-grade astrocytomas (anaplastic astrocytoma or glioblastoma) over time. The current treatment landscape involves a multimodal approach. Surgical resection is the primary treatment, with maximal safe resection associated with improved outcomes. For tumors that cannot be completely removed or that show progression, adjuvant radiation therapy and chemotherapy (commonly temozolomide) may be employed. Molecular markers, including IDH1/IDH2 mutation status and 1p/19q codeletion status, are now integral to classification and prognosis under the updated WHO classification of central nervous system tumors. IDH-mutant tumors generally carry a more favorable prognosis. Regular surveillance with MRI imaging is essential for monitoring disease progression. Despite treatment, recurrence is common, and long-term management remains a significant clinical challenge.

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