Gemistocytic astrocytoma

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]Associate Editor(s)-in-Chief: Sujit Routray, M.D. [2]

Synonyms and keywords: Gemistocytic astrocytomas; Diffuse astrocytoma; Low grade astrocytoma

Overview

Gemistocytic astrocytoma is a histologic subtype of low grade astrocytoma, with a poorer prognosis than other matched WHO grade II astrocytic tumors, and with no specific imaging features.

Pathophysiology

Pathogenesis

• Gemistocytic astrocytoma is characterized by a significant gemistocyte population, which are large cells with their cytoplasm filled with eosinophilic material displacing the nucleus eccentrically.
• It is important to note that other gliomas (e.g. fibrillary astrocytoma and oligodendroglioma) can have occasional gemistocytes, without being designated a gemistocytic astrocytoma. A cut off of 20% of the tumor cells being gemistocytes may be used before designating it as a gemistocytic astrocytoma.

Gross Pathology

• Gemistocytic astrocytoma is almost always supratentorial and usually located in the frontal lobes.

Differentiating Fibrillary Astrocytoma from other Diseases

• Gemistocytic astrocytoma must be differentiated from:

• Fibrillary astrocytoma
• Protoplasmic astrocytoma
• Oligoastrocytoma
• Stroke
• Cerebritis
• Encephalitis (herpes simplex encephalitis)
• Anaplastic astrocytoma
• Oligodendroglioma
• Angiocentric glioma

Epidemiology and Demographics

Age

• Gemistocytic astrocytoma is a rare disease that tends to affect the children and young adult population.
• The peak age at which gemistocytic astrocytoma is diagnosed ranges between 20-40 years.
• The mean age at diagnosis is 35 years.

Gender

• Males are more commonly affected with gemistocytic astrocytoma than females. The male to female ratio is approximately 1.5 to 1.

Natural History, Complications and Prognosis

Natural History

• If left untreated, patients with gemistocytic astrocytoma may progress to develop seizures, focal neurological deficits, hydrocephalus, or malignant transformation to anaplastic astrocytoma or glioblastoma multiforme.

Complications

• Common complications of gemistocytic astrocytoma include:

• Hydrocephalus
• Malignant transformation to anaplastic astrocytoma or glioblastoma multiforme.

Prognosis

• Gemistocytic astrocytoma has a poorer prognosis than the other matched WHO grade II (low-grade) astrocytic tumors ([[fibrillary astrocytoma, protoplasmic astrocytoma, and oligoastrocytoma).
• The 5-year survival rate of patients with gemistocytic astrocytoma is approximately 30%.
• The median survival time with treatment is only 2.5 years.

History and Symptoms

History

• When evaluating a patient for gemistocytic astrocytoma, you should take a detailed history of the presenting symptom (onset, duration, and progression), other associated symptoms, and a thorough family and past medical history review.

Symptoms

• Symptoms of gemistocytic astrocytoma include:

• Headaches
• Seizures
• Changes in mood
• Hemiparesis
• Changes in personality
• Changes in vision
• Speech difficulties

CT

• Head CT scan is helpful in the diagnosis of gemistocytic astrocytoma. On CT scan, gemistocytic astrocytoma is characterized by:

• Isodense or hypodense mass
• Positive mass effect
• Wispy enhancement ( most low-grade astrocytomas are without any enhancement. In fact, presence of enhancement would suggest more aggressive tumors)
• Calcification in 10-20% (more common in mixed tumors relating to an oligodendroglial components, i.e. oligoastrocytoma)
• Cystic or fluid attenuation components

Biopsy

• Biopsy of gemistocytic astrocytoma tumor, taken through a needle during a simple surgical procedure, helps to confirm the diagnosis.