Table 7.

INHAND nomenclature criteria: Malignant astrocytoma.

Indistinct border, diffusely infiltrating, sometimes multicentric, and extends over multiple brain (spinal cord) areas

Polymorphic appearance and high cellularity

Infiltrates along blood vessels (Virchow-Robin spaces)

Invasion into meninges, ependyma, and ventricles is common

Cells are generally round to fusiform, and have indistinct cell borders, cellular atypia, and pleomorphism. Cells may exhibit protoplasmic or fibrillary differentiation and prominent round or oval nuclei.

Neuronal cell bodies may persist within the neoplastic area.

Reactive astrocytes (gemistocytes) may be present.

Hemorrhage and necrosis may occur.

Necrosis with pseudopalisading is accompanied by marked cellular and nuclear pleomorphism of moderate to dense cellularity.

Abbreviation: INHAND, International Harmonization of Nomenclature and Diagnostic Criteria for Lesions in Rats and Mice.