22. Glioblastoma

Overview

Staining: HE

Organ: Brain

Description:

There are four important characteristics in glioblastomas:

• Severe atypia
• Many mitotic figures
• Pseudopalisading necrosis
• Microvascular proliferation

Microvascular proliferation is a phenomenon where the tumor contains small capillaries who are irregular and are comprised of atypical endothelial cells.

Pseudopalisading necrosis is a phenomenon where the tumor contains areas of necrosis, and this necrosis is surrounded by hypercellular regions.

Diagnosis: Glioblastoma

Pseudopalisading necrosis. The hypercellular regions form a “fence” around the necrosis.

Risk factors:

• Age 50 – 70

Theory:

Glioblastoma is a grade IV astrocytic tumor that is defined histologically be the four characteristics described above. It must be differentiated from anaplastic astrocytoma, a grade III astrocytic tumor. Anaplastic astrocytoma also shows severe atypia and many mitotic figures but no pseudopalisading necrosis or microvascular proliferation.

Tumor cells show severe atypia and there are many mitotic figures present.

Tumor on the left, showing microvascular proliferation. Normal brain parenchyme on the right for comparison.