eMedicine Specialties > Neurology > Neuro-oncology

Low-Grade Astrocytoma: Differential Diagnoses & Workup

Author: George I Jallo, MD, Associate Professor of Neurosurgery, Pediatrics and Oncology, Director, Clinical Pediatric Neurosurgery, Department of Neurosurgery, Johns Hopkins University School of Medicine
Coauthor(s): Ethan A Benardete, MD, PhD, Staff Physician, Department of Neurosurgery, New York University Medical Center
Contributor Information and Disclosures

Updated: Apr 13, 2009

Differential Diagnoses

Brainstem Gliomas
Intracranial Epidural Abscess
Cavernous Sinus Syndromes
Intracranial Hemorrhage
Cerebellar Hemorrhage
Multiple Sclerosis
Cluster Headache
Normal Pressure Hydrocephalus
Ependymoma
Oligodendroglioma
Glioblastoma Multiforme
Spinal Epidural Abscess
Head Injury
Subdural Empyema
Hydrocephalus
Tolosa-Hunt Syndrome

Other Problems to Be Considered

Brainstem syndromes
Cerebritis or cerebral abscess
Cavernous angioma or arteriovenous malformation
Hamartoma
Stroke or infarct

Workup

Laboratory Studies

No specific laboratory test is available for low-grade glioma. If an endocrine abnormality is suggested, then the appropriate studies may be ordered, but laboratory tests are not indicated routinely for diagnosis of low-grade glioma.

Imaging Studies

  • Both CT scan and MRI can aid in the diagnosis of low-grade glioma. Generally, MRI is considered the study of choice. However, in an emergency setting a noncontrast CT scan may be ordered first.
  • Patients with new-onset headache, seizure, weakness, or numbness frequently undergo a CT scan first. Typical CT findings of a low-grade glioma show lower attenuation than the surrounding brain (see Media file 1). A mild mass effect may be noted. Obstructive hydrocephalus can be confirmed. Low-grade gliomas also may show evidence of calcification. If a contrast CT scan is obtained, the tumor usually does not enhance.

    A 28-year-old male taxi driver presented to the e...

    A 28-year-old male taxi driver presented to the emergency department after having a seizure. Noncontrast head CT scan was obtained showing the typical appearance of a low-grade astrocytoma. The lesion in the mesial left frontal lobe was hypodense on CT scan.

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    A 28-year-old male taxi driver presented to the e...

    A 28-year-old male taxi driver presented to the emergency department after having a seizure. Noncontrast head CT scan was obtained showing the typical appearance of a low-grade astrocytoma. The lesion in the mesial left frontal lobe was hypodense on CT scan.

  • On MRI, low-grade gliomas show decreased signal relative to surrounding brain on T1 sequences (see Media files 2-3, Media files 6-8). On T2 sequences, higher signal reflects both the tumor and surrounding edema (see Media files 4-5). Pilocytic astrocytomas often are associated with a cyst, which may be particularly prominent on T2-weighted sequences.
  • MRI of the spinal cord is also the study of choice if an intramedullary low-grade astrocytoma is suspected. On MRI, widening of the spinal cord and frequently an associated cyst are noted. The tumor may show a variable degree of enhancement.

Other Tests

  • Electroencephalography (EEG) may be performed on a patient with new-onset seizures; however, no EEG findings are specific to low-grade glioma. However, generalized, diffuse slowing and/or epileptogenic spikes can be seen over the area of the tumor.
  • Positron emission tomography (PET) and single-photon emission computed tomography (SPECT) imaging sometimes are used to try to differentiate low-grade gliomas from either high-grade tumors or other types of pathology. Typically, low-grade gliomas show hypometabolism via PET or SPECT while high-grade gliomas are hypermetabolic. This information may be useful in guiding further therapy.

Procedures

Lumbar puncture is generally contraindicated in patients with elevated intracranial pressure, which may occur in the setting of a brain tumor. Cerebrospinal fluid (CSF) studies do not aid in the diagnosis of low-grade glioma.

Histologic Findings

As briefly reviewed already, the histologic findings in low-grade astrocytomas depend on the type of tumor. Low-grade infiltrating astrocytomas are characterized by mild cellular proliferation and atypia. High-grade features, such necrosis or endothelial cell proliferation, are not present.

Pilocytic astrocytomas show piloid (hairlike) cells in 2 patterns: dense fascicles and loose arrangements. They also may show some degree of microvascular proliferation and necrosis, but these do not indicate malignant potential in these relatively well-circumscribed tumors. Pilocytic astrocytomas frequently are associated with a cyst.

Pleomorphic xanthoastrocytoma have a high degree of astrocytic pleomorphism as well as lipidized giant cells. Usually no necrosis or endothelial proliferation is noted. Subependymal giant-cell astrocytomas demonstrate several types of cells, typically including small elongated cells as well as giant, multinucleated globoid cells.

More on Low-Grade Astrocytoma

Overview: Low-Grade Astrocytoma
Differential Diagnoses & Workup: Low-Grade Astrocytoma
Treatment & Medication: Low-Grade Astrocytoma
Follow-up: Low-Grade Astrocytoma
Multimedia: Low-Grade Astrocytoma
References
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References

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  13. McCormack BM, Miller DC, Budzilovich GN, et al. Treatment and survival of low-grade astrocytoma in adults--1977-1988. Neurosurgery. Oct 1992;31(4):636-42; discussion 642. [Medline].

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  15. Morantz R A. Low-grade astrocytomas. In: Kaye AH, Laws ER Jr, eds. Brain Tumors: An Encyclopedic Approach. New York: Churchill Livingstone; 1995:433-48.

  16. Salcman M. Radical surgery for low-grade glioma. Clin Neurosurg. 1990;36:353-66. [Medline].

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Further Reading

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Keywords

low grade astrocytoma, central nervous system neoplasms, primary brain tumor, treatment, symptoms, glioblastoma multiforme, GBM, juvenile pilocytic astrocytoma, JPA, pleomorphic xanthoastrocytoma, PXA, subependymal giant-cell astrocytoma, SGCA, low-grade astrocytoma, CNS neoplasm, glioma

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Contributor Information and Disclosures

Author

George I Jallo, MD, Associate Professor of Neurosurgery, Pediatrics and Oncology, Director, Clinical Pediatric Neurosurgery, Department of Neurosurgery, Johns Hopkins University School of Medicine
George I Jallo, MD is a member of the following medical societies: American Association of Neurological Surgeons, American College of Surgeons, American Medical Association, and American Society of Pediatric Neurosurgeons
Disclosure: Nothing to disclose.

Coauthor(s)

Ethan A Benardete, MD, PhD, Staff Physician, Department of Neurosurgery, New York University Medical Center
Ethan A Benardete, MD, PhD is a member of the following medical societies: American Association of Neurological Surgeons and American Medical Association
Disclosure: Nothing to disclose.

Medical Editor

Rodrigo O Kuljis, MD, Esther Lichtenstein Professor of Psychiatry and Neurology, Director, Division of Cognitive and Behavioral Neurology, Department of Neurology, University of Miami School of Medicine
Rodrigo O Kuljis, MD is a member of the following medical societies: American Academy of Neurology and Society for Neuroscience
Disclosure: Nothing to disclose.

Pharmacy Editor

Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine
Disclosure: Nothing to disclose.

Managing Editor

Jorge Kattah, MD, Head, Program Director, Professor, Department of Neurology, University of Illinois College of Medicine at Peoria
Jorge Kattah, MD is a member of the following medical societies: American Academy of Neurology, American Neurological Association, and New York Academy of Sciences
Disclosure: Biogen Honoraria Consulting; Bayer Corporation Honoraria Consulting

CME Editor

Matthew J Baker, MD, Consulting Staff, Collier Neurologic Specialists, Naples Community Hospital
Matthew J Baker, MD is a member of the following medical societies: American Academy of Neurology
Disclosure: Nothing to disclose.

Chief Editor

Nicholas Y Lorenzo, MD, Chief Editor, eMedicine Neurology; Consulting Staff, Neurology Specialists and Consultants
Nicholas Y Lorenzo, MD is a member of the following medical societies: Alpha Omega Alpha and American Academy of Neurology
Disclosure: Nothing to disclose.

 
 
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