Gliomas (gliomas are the most common primary intracranial neoplasm in adults, and glioblastoma is the most common type of glioma)
1. Fibrillary Astrocytoma, Anaplastic Astrocytoma and Glioblastoma (these tumors arise from astrocytes) -- this is a series of tumor grades, with well-differentiated fibrillary astrocytoma considered benign (by histologic criteria), and glioblastoma considered the most malignant. The two images illustrate one of the gross appearance differences between low-grade astrocytoma and malignant glioblastoma: low-grade astrocytomas generally do NOT show gross demarcation between the tumor and surrounding neural tissue, but glioblastomas DO show an apparent demarcation, although tumor cells infiltrate into the normal-appearing tissue.
Location: more often in cerebral hemispheres, but may occur anywhere
Signs and symptoms: related to location of tumor plus displacement effects
Incidence: for glioblastoma, increases with patient age; rare before age 30
Prognosis: Survival is inversely related to grade and age of the patient. Low grade neoplasms usually progress to high grade neoplasms with time. For glioblastoma, most patients survive less than 1 year after diagnosis.
Gross pathology: varies with degree of malignancy.
-----Lower grades (grades 1-2; fibrillary astrocytoma) are firm, usually white (not hemorrhagic), appear poorly circumscribed.
-----Grades 3-4 (anaplastic astrocytoma and glioblastoma) look well circumscribed, but infiltrate widely. The cut surface has many colors and consistencies produced by areas of hemorrhage, necrosis and cysts. Marked edema is characteristic.