What is the key difference between reactive gliosis and glioma?

• A. Reactive gliosis is a non-neoplastic astrocytic response to injury
• B. Reactive gliosis forms a capsule around lesions
• C. Glioma is always benign
• D. Reactive gliosis occurs only after infection

Answer: (A)

The main distinction is that reactive gliosis is a non-neoplastic astrocytic response to CNS injury, resulting in a glial scar and local hypertrophy with increased GFAP, but without true tumor growth. Glioma, on the other hand, is a neoplastic proliferation of glial cells that can form an infiltrative mass, show cellular atypia and mitotic activity, and has potential for malignant behavior.

In reactive gliosis, the astrocytes react to injury rather than multiply as a true tumor; they aim to help contain damage and repair but do not exhibit clonal neoplastic expansion. In glioma, the glial cells undergo uncontrolled growth, invade surrounding tissue, and can progress through grades of malignancy.

Why the other statements don’t fit: a glial scar is not a true capsule around a lesion, so forming a capsule is not a defining feature of reactive gliosis; gliomas are not always benign—high-grade gliomas are clearly malignant; and reactive gliosis can occur after many insults (not just infection), including trauma, ischemia, and inflammation.