Core histopathologic criteria used to grade astrocytomas (WHO)?

• A. Edema, necrosis, gliosis, calcification.
• B. Inflammatory infiltrate, edema, demyelination, gliosis.
• C. Vascular proliferation, necrosis, lipoblasts, mitotic index.
• D. Cellular atypia, mitotic activity, microvascular proliferation, and necrosis.

Answer: (D)

Grading astrocytomas by the WHO is based on histologic signs that reflect how aggressive the tumor is. The essential features clinicians look for are cellular atypia, mitotic activity, microvascular proliferation, and necrosis. Cellular atypia shows abnormal nuclear appearance, indicating abnormal cell behavior. If mitotic activity is present, it points to active tumor growth and pushes the grade higher. The combination of mitotic activity with microvascular proliferation or necrosis designates the highest grade, with necrosis and/or microvascular proliferation defining glioblastoma (the most advanced grade). Other observations like edema, gliosis, calcification, inflammatory infiltrates, or demyelination are not used to determine the astrocytoma grade. So the four features—cellular atypia, mitotic activity, microvascular proliferation, and necrosis—form the core histologic criteria for grading follows WHO criteria.