Gemistocytic astrocytoma

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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.[1]

Historical Perspective

  • Gemistocytic astrocyte was first described by Franz Nissl in the 20th century.[2]

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.[3]
  • It is important to note that other gliomas 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.
  • Other CNS tumors and conditions that have gemistocytes or gemistocyte-like cells include:[2]

Gross Pathology

  • On gross pathology, gemistocytic astrocytoma is characterized by:[2]
  • Gray-tan mass
  • Well-defined borders
  • Soft texture
  • Cystic architecture

Microscopic Pathology

  • On microscopic histopathological analysis, gemistocytic astrocytoma is characterized by:[3][5][6]
  • Neoplastic fibrillary astrocytes embedded in the tumor matrix
  • Gemistocytes > 20% of the tumor cells
  • Large, plump astrocytes
  • Abundant eosinophilic cytoplasm
  • Eccentric nuclei
  • Low cellular density
  • Mild nuclear atypia (enlarged, irregular contour, hyperchromasia, and coarsened nuclear chromatin pattern)
  • Mucinous fluid containing microcystic spaces
  • Perivascular lymphocytic infiltrate
  • Abscence of mitoses, microvascular proliferation, and necrosis

Immunohistochemistry

  • Gemistocytic astrocytoma is demonstrated by positivity to tumor marker such as GFAP.[5]

Differentiating Gemistocytic Astrocytoma from other Diseases

  • Gemistocytic astrocytoma must be differentiated from:[7]

Epidemiology and Demographics

Age

  • Gemistocytic astrocytoma is a rare disease that tends to affect children and young adults.[8]
  • 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.[8]

Natural History, Complications and Prognosis

Natural History

Complications

  • Common complications of gemistocytic astrocytoma include:[5][9]

Prognosis

  • Gemistocytic astrocytoma has a poorer prognosis than the other matched WHO grade II (low-grade) astrocytic tumors (fibrillary astrocytoma, protoplasmic astrocytoma, and oligoastrocytoma).[1]
  • The 5-year survival rate of patients with gemistocytic astrocytoma is approximately 30%.[10]
  • The median survival time with treatment is only 2.5 years.
  • Favorable prognostic factors for gemistocytic astrocytoma include:[6]
  • Age < 50 years
  • Occurrence of seizures as the initial symptom
  • Pre-operative symptoms lasting more than 6 months

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:[9]

CT

  • Head CT scan is helpful in the diagnosis of gemistocytic astrocytoma. On CT scan, gemistocytic astrocytoma is characterized by:[11]
  • 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

MRI

  • Brain MRI is helpful in the diagnosis of gemistocytic astrocytoma. On MRI, gemistocytic astrocytoma is characterized by:[11]
MRI component Findings

T1

  • Isointense to hypointense compared to white matter
  • Usually confined to the white matter and causes expansion of the adjacent cortex

T2

  • Hyperintense compared to white matter
  • Always follow the white matter distribution and cause expansion of the surrounding cortex
  • Cortex may also be involved in late cases, in comparison to the oligodendroglioma, which is a cortical based tumor from the start
  • "Microcystic changes" along the lines of spread of the infiltrative astrocytoma is a very unique behavior for the infiltrative astrocytoma, however, it is only appreciated in a few number of cases
  • Hyperintense T2 signal is not related to cellularity or cellular atypia, but rather edema, demyelination, and other degenerative changes

T1 with contrast

  • No enhancement
  • Small ill-defined areas of enhancement are not rare; however, when enhancement is seen, it should be considered as a warning sign for progression to a higher grade

Diffusion weighted imaging (DWI)

  • No restricted diffusion
  • Increased diffusibility is the key to differentiate the gemistocytic astrocytoma from the acute ischemia

Other Imaging Findings

Magnetic Resonance Spectroscopy

  • Elevated choline peak, low N-Acetylaspartate peak, elevated choline:creatine ratio
  • Elevated myo-inositol (mI) and mI/creatine ratio
  • Lack of the lactate peak seen at 1:33
  • Lactate peak represents the necrosis seen in aggressive tumors (WHO grade IV)

Magnetic Resonance Perfusion

  • MR perfusion may be helpful in the diagnosis of gemistocytic astrocytoma, which demonstrates no elevation of relative cerebral blood volume (rCBV).[11]

Biopsy

  • Biopsy of the gemistocytic astrocytoma tumor, taken through a needle during a simple surgical procedure, helps to confirm the diagnosis.[12]

Treatment

  • The predominant therapy for gemistocytic astrocytoma is surgical resection. Adjunctive radiation and nitrosourea-based chemotherapy may be required.[6]
  • Surgery: Since gemistocytic astrocytoma can behave aggressively, surgery is the mainstay of treatment.
  • Radiotherapy: Radiotherapy may be used in gemistocytic astrocytoma post-operatively or at the time of recurrence or progression.[6][12]
  • Chemotherapy: Chemotherapy may have a role in recurrent and de-differentiated tumors.[12]


 
 
 
 
 
 
 
 
 
 
 
 
Treatment of gemistocytic astrocytoma
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Surgery
 
 
 
Radiotherapy
 
 
 
Chemotherapy
 
 
 
 
 
 
 
 
 
 
 
 
 

References

  1. 1.0 1.1 Gemistocytic astrocytoma. Dr Henry Knipe and A.Prof Frank Gaillard et al. Radiopaedia 2016. http://radiopaedia.org/articles/gemistocytic-astrocytoma. Accessed on January 8, 2016
  2. 2.0 2.1 2.2 Tihan, Tarik; Vohra, Poonam; Berger, Mitchel S.; Keles, G. Evren (2005). "Definition and Diagnostic Implications of Gemistocytic Astrocytomas: A Pathological Perspective". Journal of Neuro-Oncology. 76 (2): 175–183. ISSN 0167-594X. doi:10.1007/s11060-005-4897-2. 
  3. 3.0 3.1 Pathology of gemistocytic astrocytoma. Dr Henry Knipe and A.Prof Frank Gaillard et al. Radiopaedia 2016. http://radiopaedia.org/articles/gemistocytic-astrocytoma. Accessed on January 8, 2016
  4. Radiographic features of gemistocytic astrocytoma. Dr Henry Knipe and A.Prof Frank Gaillard et al. Radiopaedia 2016. http://radiopaedia.org/articles/gemistocytic-astrocytoma. Accessed on January 8, 2016
  5. 5.0 5.1 5.2 Pathology of low grade infiltrative astrocytoma. Dr Ahmed Abd Rabou and A.Prof Frank Gaillard et al. Radiopaedia 2016. http://radiopaedia.org/articles/low-grade-infiltrative-astrocytoma. Accessed on January 8, 2016
  6. 6.0 6.1 6.2 6.3 6.4 Krouwer HG, Davis RL, Silver P, Prados M (1991). "Gemistocytic astrocytomas: a reappraisal.". J Neurosurg. 74 (3): 399–406. PMID 1993905. doi:10.3171/jns.1991.74.3.0399. 
  7. Differential diagnosis of low grade infiltrative astrocytoma. Dr Ahmed Abd Rabou and A.Prof Frank Gaillard et al. Radiopaedia 2016. http://radiopaedia.org/articles/low-grade-infiltrative-astrocytoma. Accessed on January 5, 2016
  8. 8.0 8.1 Epidemiology of gemistocytic astrocytoma. Dr Ahmed Abd Rabou and A.Prof Frank Gaillard et al. Radiopaedia 2016. http://radiopaedia.org/articles/low-grade-infiltrative-astrocytoma. Accessed on January 8, 2016
  9. 9.0 9.1 9.2 Clinical presentation of low grade infiltrative astrocytoma. Dr Ahmed Abd Rabou and A.Prof Frank Gaillard et al. Radiopaedia 2016. http://radiopaedia.org/articles/low-grade-infiltrative-astrocytoma. Accessed on January 8, 2016
  10. Treatment and prognosis of gemistocytic astrocytoma. Dr Henry Knipe and A.Prof Frank Gaillard et al. Radiopaedia 2016. http://radiopaedia.org/articles/gemistocytic-astrocytoma. Accessed on January 8, 2016
  11. 11.0 11.1 11.2 11.3 Radiographic features of low grade infiltrative astrocytoma. Dr Ahmed Abd Rabou and A.Prof Frank Gaillard et al. Radiopaedia 2016. http://radiopaedia.org/articles/low-grade-infiltrative-astrocytoma. Accessed on January 8, 2016
  12. 12.0 12.1 12.2 Treatment and prognosis of low grade infiltrative astrocytoma. Dr Ahmed Abd Rabou and A.Prof Frank Gaillard et al. Radiopaedia 2016. http://radiopaedia.org/articles/low-grade-infiltrative-astrocytoma. Accessed on January 8, 2016

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