Fibrillary Astrocytoma, WHO Grade II
Higher magnification of the previous image showing slight increase in glial cellularity, mild nuclear pleomorphism, and a fibrillary background. In low-grade astrocytomas, the transition from tumor to normal tissue is often indistinct. Low-grade astrocytomas frequently harbor mutations involving p53 and PDGF-A and its receptor. Progression to high-grade astrocytomas is usually linked to further mutations involving RB and p16/CDKNaA tumor suppressor genes.