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| ==Overview== | | ==Overview== |
| Fibrillary astrocytoma is the most common type of diffuse low grade astrocytoma. According to the WHO classification of tumors of the central nervous system, it is classified as a ''WHO grade II'' tumor.<ref name=overviewfa1>Fibrillary astrocytoma. Dr Henry Knipe and A.Prof Frank Gaillard et al. Radiopaedia 2016. http://radiopaedia.org/articles/fibrillary-astrocytoma. Accessed on January 4, 2015</ref> Unlike the other variants of diffuse low grade gliomas (e.g. gemistocytic astrocytoma; protoplasmic astrocytoma; [[oligoastrocytoma]]) or the focal low grade gliomas (e.g. [[pilocytic astrocytoma]]; [[subependymal giant cell astrocytoma]]), fibrillary astrocytomas are often merely referred to as a low grade glioma.<ref name=overviewfa1>Fibrillary astrocytoma. Dr Henry Knipe and A.Prof Frank Gaillard et al. Radiopaedia 2016. http://radiopaedia.org/articles/fibrillary-astrocytoma. Accessed on January 4, 2015</ref>
| | Gemistocytic astrocytoma is a histologic subtype of [[low grade astrocytoma]], with a poorer prognosis than other matched WHO grade II tumors, and with no specific imaging features.<ref name=overviewga1>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</ref> |
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| ==Pathophysiology==
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| ===Pathogenesis===
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| *Fibrillary astrocytoma arises from the neoplastic [[astrocyte]]s, a type of glial cell found in the central nervous system.<ref name=patogenesisfabjh>Pathology of fibrillary astrocytoma. Wikipedia 2016. https://en.wikipedia.org/wiki/Fibrillary_astrocytoma. Accessed on January 4, 2016</ref>
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| *Fibrillary astrocytoma is predominantly composed of a tumor matrix rich with neuroglial fibrils, which give the tumor its name and firm consistency.<ref name=pathogenesisfa1>Pathology of fibrillary astrocytoma. Dr Henry Knipe and A.Prof Frank Gaillard et al. Radiopaedia 2016. http://radiopaedia.org/articles/fibrillary-astrocytoma. Accessed on January 4, 2016</ref>
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| *As the alternative name of "diffuse astrocytoma" implies, the outline of the tumor is not clearly visible in scans, because the borders of the neoplasm tend to send out tiny microscopic fibrillary tentacles that spread into the surrounding brain tissue. These tentacles intermingle with healthy brain cells, making complete surgical removal difficult. However, they are low grade tumors, with a slow rate of growth, so that patients commonly survive longer than those with otherwise similar types of brain tumor, such as glioblastoma multiforme.
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| ===Gross Pathology===
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| *On gross pathology, fibrillary astrocytoma is characterized by:<ref name=pathogenesisfa1>Pathology of fibrillary astrocytoma. Dr Henry Knipe and A.Prof Frank Gaillard et al. Radiopaedia 2016. http://radiopaedia.org/articles/fibrillary-astrocytoma. Accessed on January 4, 2016</ref>
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| :*Mass with ill-defined borders
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| :*Firm in consistency
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| :*Loss of normal gray-white matter junction
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| :*Less vascular
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| ===Microscopic Pathology===
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| *On microscopic histopathological analysis, fibrillary astrocytoma is characterized by:<ref name=pathogenesisfa1>Pathology of fibrillary astrocytoma. Dr Henry Knipe and A.Prof Frank Gaillard et al. Radiopaedia 2016. http://radiopaedia.org/articles/fibrillary-astrocytoma. Accessed on January 4, 2016</ref>
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| :*Neoplastic fibrillary astrocytes embedded in the tumor matrix
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| :*Low cellular density
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| :*[[atypia|Mild nuclear atypia]] (enlarged, irregular contour, hyperchromasia, and coarsened nuclear chromatin pattern)
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| :*Mucinous fluid containing microcystic spaces
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| :*No [[mitoses]], microvascular proliferation, and [[necrosis]]
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| ===Immunohistochemistry===
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| *Fibrillary astrocytoma is demonstrated by positivity to tumor marker such as [[GFAP]].<ref name=pathogenesisfa1>Pathology of fibrillary astrocytoma. Dr Henry Knipe and A.Prof Frank Gaillard et al. Radiopaedia 2016. http://radiopaedia.org/articles/fibrillary-astrocytoma. Accessed on January 4, 2016</ref>
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| ==Differentiating Fibrillary Astrocytoma from other Diseases== | | ==Differentiating Fibrillary Astrocytoma from other Diseases== |
| *Fibrillary astrocytoma must be differentiated from:<ref name=ddxfa1>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</ref> | | *Gemistocytic astrocytoma must be differentiated from:<ref name=ddxfa1>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</ref> |
| :*Gemistocytic astrocytoma | | :*[[Fibrillary astrocytoma]] |
| :*Protoplasmic astrocytoma | | :*Protoplasmic astrocytoma |
| :*[[Oligoastrocytoma]] | | :*[[Oligoastrocytoma]] |
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| :*Angiocentric glioma | | :*Angiocentric glioma |
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| ==Epidemiology and Demographics==
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| ===Prevalence===
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| *Fibrillary astrocytoma constitutes approximately 10-15% of all astrocytic brain tumors.<ref name=prevalenxefa1>Prevalence/Incidence of Diffuse Astrocytoma/Fibrillary Astrocytoma. Brain tumor foundation of Canada 2016. http://www.braintumour.ca/4877/diffuse-astrocytoma-/-fibrillary-astrocytoma. Accessed on January 4, 2016</ref>
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| ===Age===
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| *Fibrillary astrocytoma is a rare disease that tends to affect the young adult population.<ref name=agefa1>Epidemiology of fibrillary astrocytoma. Dr Henry Knipe and A.Prof Frank Gaillard et al. Radiopaedia 2016. http://radiopaedia.org/articles/fibrillary-astrocytoma. Accessed on January 4, 2016</ref><ref name=agefa1bvjhv>Typical age range of Diffuse Astrocytoma/Fibrillary Astrocytoma. Brain tumor foundation of Canada 2016. http://www.braintumour.ca/4877/diffuse-astrocytoma-/-fibrillary-astrocytoma. Accessed on January 4, 2016</ref>
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| *The median age at diagnosis is 35 years.<ref name=agefa1>Epidemiology of fibrillary astrocytoma. Dr Henry Knipe and A.Prof Frank Gaillard et al. Radiopaedia 2016. http://radiopaedia.org/articles/fibrillary-astrocytoma. Accessed on January 4, 2016</ref>
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| ===Gender===
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| *Males are more commonly affected with fibrillary astrocytoma than females. The male to female ratio is approximately 1.5 to 1.<ref name=agefa1>Epidemiology of fibrillary astrocytoma. Dr Henry Knipe and A.Prof Frank Gaillard et al. Radiopaedia 2016. http://radiopaedia.org/articles/fibrillary-astrocytoma. Accessed on January 4, 2016</ref>
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| ==Natural History, Complications and Prognosis==
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| ===Natural History===
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| *If left untreated, patients with fibrillary astrocytoma may progress to develop [[seizures]], focal neurological deficits, and [[hydrocephalus]].<ref name=sympfa3>Clinical presentation of fibrillary astrocytoma. Dr Henry Knipe and A.Prof Frank Gaillard et al. Radiopaedia 2016. http://radiopaedia.org/articles/fibrillary-astrocytoma. Accessed on January 4, 2016</ref>
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| ===Complications===
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| *Common complications of fibrillary astrocytoma include:<ref name=sympfa3>Clinical presentation of fibrillary astrocytoma. Dr Henry Knipe and A.Prof Frank Gaillard et al. Radiopaedia 2016. http://radiopaedia.org/articles/fibrillary-astrocytoma. Accessed on January 4, 2016</ref>
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| :*[[Hydrocephalus]]
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| :*Side-effects of neurosurgery
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| ===Prognosis===
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| *The 5-year survival rate of patients with fibrillary astrocytoma is approximately 45%.<ref name="PenmanFaulkner2015">{{cite journal|last1=Penman|first1=Catherine Louise|last2=Faulkner|first2=Claire|last3=Lowis|first3=Stephen P.|last4=Kurian|first4=Kathreena M.|title=Current Understanding of BRAF Alterations in Diagnosis, Prognosis, and Therapeutic Targeting in Pediatric Low-Grade Gliomas|journal=Frontiers in Oncology|volume=5|year=2015|issn=2234-943X|doi=10.3389/fonc.2015.00054}}</ref>
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| *Complete surgical excision of fibrillary astrocytoma is associated with a good prognosis.<ref name=prognosisfa1>Treatment of fibrillary astrocytoma. Wikipedia 2016. https://en.wikipedia.org/wiki/Fibrillary_astrocytoma. Accessed on January 5, 2016</ref>
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| ==Symptoms==
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| *Symptoms of fibrillary astrocytoma include:<ref name=symptomsfa1>Symptoms and diagnosis of fibrillary astrocytoma. Wikipedia 2016. https://en.wikipedia.org/wiki/Fibrillary_astrocytoma. Accessed on January 4, 2015</ref><ref name=symptomsfa2>Symptoms of diffuse Astrocytoma/fibrillary Astrocytoma. Brain tumour foundation of Canada 2016. http://www.braintumour.ca/4877/diffuse-astrocytoma-/-fibrillary-astrocytoma. Accessed on January 4, 2016</ref><ref name=sympfa3>Clinical presentation of fibrillary astrocytoma. Dr Henry Knipe and A.Prof Frank Gaillard et al. Radiopaedia 2016. http://radiopaedia.org/articles/fibrillary-astrocytoma. Accessed on January 4, 2016</ref>
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| :*[[Headaches]] (earliest symptom)
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| :*[[Seizures]] (most common symptom)
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| :*[[Mood (psychology)|Changes in mood]]
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| :*[[Hemiparesis]]
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| :*[[Personality pathology|Changes in personality]]
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| :*[[vision loss|Changes in vision]]
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| :*[[Speech difficulties]]
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| ==CT==
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| *Head CT scan is helpful in the diagnosis of fibrillary astrocytoma. On CT scan, fibrillary astrocytoma is characterized by:<ref name=radfa1>Radiographic features of fibrillary astrocytoma. Dr Henry Knipe and A.Prof Frank Gaillard et al. Radiopaedia 2016. http://radiopaedia.org/articles/fibrillary-astrocytoma. Accessed on January 4, 2016</ref>
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| :*Isodense or hypodense mass
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| :*Positive mass effect
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| :*No enhancement
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| :*Calcification in 10-20% (more common in mixed tumors relating to an oligodendroglial components, i.e. [[oligoastrocytoma]])
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| :*Cystic or fluid attenuation components (more common in gemistocytic astrocytoma and protoplasmic astrocytoma)
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| ==MRI==
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| *Brain MRI is helpful in the diagnosis of fibrillary astrocytoma. On MRI, fibrillary astrocytoma is characterized by:<ref name=radfa1>Radiographic features of fibrillary astrocytoma. Dr Henry Knipe and A.Prof Frank Gaillard et al. Radiopaedia 2016. http://radiopaedia.org/articles/fibrillary-astrocytoma. Accessed on January 4, 2016</ref>
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| ! style="background: #4479BA; width: 150px;" | {{fontcolor|#FFF|MRI component}}
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| ! style="background: #4479BA; width: 370px;" | {{fontcolor|#FFF|Findings}}
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| T1
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| | style="padding: 5px 5px; background: #F5F5F5;" |
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| *Isointense to hypointense compared to white matter
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| T2
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| *Hyperintense compared to white matter
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| T1 with contrast
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| *Little or no enhancement
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| ==Biopsy==
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| *[[Biopsy]] of fibrillary astrocytoma tumor mass, taken through a needle during a simple surgical procedure, helps to confirm the diagnosis.<ref name=rxfa1>Treatment and prognosis of fibrillary astrocytoma. Dr Henry Knipe and A.Prof Frank Gaillard et al. Radiopaedia 2016. http://radiopaedia.org/articles/fibrillary-astrocytoma. Accessed on January 5, 2015</ref>
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| ==Other Diagnostic Studies==
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| ===Magnetic Resonance Spectroscopy===
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| *[[Nuclear magnetic resonance spectroscopy|MR spectroscopy]] may be helpful in the diagnosis of fibrillary astrocytoma, which demonstrates elevated [[choline]]:[[creatine]] ratio.<ref name=radfa1>Radiographic features of fibrillary astrocytoma. Dr Henry Knipe and A.Prof Frank Gaillard et al. Radiopaedia 2016. http://radiopaedia.org/articles/fibrillary-astrocytoma. Accessed on January 4, 2016</ref>
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| ===Magnetic Resonance Perfusion===
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| *[[Perfusion weighted imaging|MR perfusion]] may be helpful in the diagnosis of fibrillary astrocytoma, which demonstrates no elevation of relative cerebral blood volume (rCBV).<ref name=radfa1>Radiographic features of fibrillary astrocytoma. Dr Henry Knipe and A.Prof Frank Gaillard et al. Radiopaedia 2016. http://radiopaedia.org/articles/fibrillary-astrocytoma. Accessed on January 4, 2016</ref>
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| ===Electroencephalogram===
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| *[[Electroencephalogram|Electroencephalogram (EEG)]] is performed in cases of fibrillary astrocytoma to record the continuous electrical activity of the brain and locate the seizure activity.<ref name=radfa1>Radiographic features of fibrillary astrocytoma. Dr Henry Knipe and A.Prof Frank Gaillard et al. Radiopaedia 2016. http://radiopaedia.org/articles/fibrillary-astrocytoma. Accessed on January 4, 2016</ref>
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| ==Treatment==
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| The treatment options for fibrillary astrocytoma include:<ref name=rxfa1>Treatment of fibrillary astrocytoma. Wikipedia 2016. https://en.wikipedia.org/wiki/Fibrillary_astrocytoma. Accessed on January 4, 2016</ref>
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| {{familytree/start |summary=Treatment of fibrillary astrocytoma}}
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| {{familytree |boxstyle=background: #DCDCDC;| | | | | | | | | | | | | A01| | | | | | | | | | | | | |A01=<div style="width: 12em; padding:0.2em;">'''Treatment of fibrillary astrocytoma'''</div>}}
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| {{familytree |boxstyle=background: #DCDCDC;| | | | | | | B01 | | B02 | | B03 | | B04 | | | | | | | | | | | | | |B01=<div style="width: 9em; padding:0.2em;">'''Surgery''' </div>|B02=<div style="width: 9em; padding:0.2em;">'''Radiotherapy'''</div>|B03=<div style="width: 9em; padding:0.2em;">'''Radiosurgery'''</div>|B04=<div style="width: 9em; padding:0.2em;">'''Chemotherapy'''</div>}}
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| ===Surgery===
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| *The treatment of fibrillary astrocytoma depends on the clinical presentation, tumor size, and location.<ref name=rxfa1>Treatment and prognosis of fibrillary astrocytoma. Dr Henry Knipe and A.Prof Frank Gaillard et al. Radiopaedia 2016. http://radiopaedia.org/articles/fibrillary-astrocytoma. Accessed on January 5, 2015</ref>
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| *The infiltrating growth of microscopic tentacles in fibrillary astrocytoma makes complete surgical removal difficult or impossible, without injuring brain tissue needed for normal neurological function. However, [[surgery]] can still reduce or control tumor size.<ref name=prognosisfa1>Treatment of fibrillary astrocytoma. Wikipedia 2016. https://en.wikipedia.org/wiki/Fibrillary_astrocytoma. Accessed on January 5, 2016</ref>
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| ===Radiotherapy===
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| *[[radiotherapy|Standard radiotherapy]] for fibrillary astrocytoma requires from ten to thirty sessions, depending on the sub-type of the tumor, and may sometimes be performed after surgical resection to improve outcomes and survival rates.<ref name=prognosisfa1>Treatment of fibrillary astrocytoma. Wikipedia 2016. https://en.wikipedia.org/wiki/Fibrillary_astrocytoma. Accessed on January 5, 2016</ref>
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| ===Radiosurgery===
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| *[[Radiosurgery]] uses computer modelling to focus minimal radiation doses at the exact location of the tumor, while minimizing the dose to the surrounding healthy brain tissue.<ref name=prognosisfa1>Treatment of fibrillary astrocytoma. Wikipedia 2016. https://en.wikipedia.org/wiki/Fibrillary_astrocytoma. Accessed on January 5, 2016</ref>
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| *Radiosurgery may be a used as a complementary treatment post-surgery, or it may represent the primary treatment technique.
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| ===Chemotherapy===
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| *[[Chemotherapy]] may have a role in treating recurrent/de-differentiated fibrillary astrocytomas.<ref name=rxfa1>Treatment and prognosis of fibrillary astrocytoma. Dr Henry Knipe and A.Prof Frank Gaillard et al. Radiopaedia 2016. http://radiopaedia.org/articles/fibrillary-astrocytoma. Accessed on January 5, 2015</ref>
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| *Although chemotherapy for fibrillary astrocytoma improves overall survival, it is effective only in about 20% of the cases.<ref name=prognosisfa1>Treatment of fibrillary astrocytoma. Wikipedia 2016. https://en.wikipedia.org/wiki/Fibrillary_astrocytoma. Accessed on January 5, 2016</ref>
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| ==References== | | ==References== |