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Pilocytic astrocytoma

Changed by Frank Gaillard, 29 Apr 2023
Back to revision history
Disclosures - updated 6 Dec 2022:
  • Biogen Australia Pty Ltd, Investigator-Initiated Research Grant for CAD software in multiple sclerosis: finished Oct 2021 (past)

Updates to Article Attributes

Body was changed:

Pilocytic astrocytomas, also known as juvenile pilocytic astrocytomas, are circumscribed astrocytic gliomas that tendtypically to occur in young patients. TheyThe majority of sporadic pilocytic astrocytomas arise from the cerebellum, whereas in the setting of neurofibromatosis type 1, they often involve the optic chiasm and pathway. In adults, they are typically supratentorial 11.

Pilocytic astrocytomas are considered WHO grade 1 tumours in the current WHO classification of CNS tumours and correspondingly have a relatively good prognosis.

These tumours have a range of imaging appearances, with the majority presenting as a large cystic lesion with a brightly enhancing mural nodule. Calcification can be present in around one-fifth of cases.

The majority of pilocytic astrocytomas arise from the cerebellum. Optic pathway gliomas and spinal cord pilocytic astrocytomas are discussed separately.

The The remainder of this article focuses on a general discussion of pilocytic astrocytomas, particularly those in the cerebellum. 

Epidemiology

Pilocytic astrocytomas are tumours of young people, with 7569% occurring in the first two decades of life, typically late in the first decade (9-10 years)11. There is no recognised gender predispositionThey do, however, also occasionally arise in adults 11.

Although they only account for 0.6-5.1% of all intracranial neoplasms (1.7-7% of all glial tumours), they are the most common primary brain tumour of childhood (15%) 7 and the second most common paediatric posterior fossa tumour (25-35%) after medulloblastomas 10.

Associations

There is a strong association with neurofibromatosis type 1 (NF1). NF1-associated tumours have a tendency to affect the optic nerves and chiasm (see: optic pathway glioma). The association between NF1 and pilocytic astrocytomas is so strong that up to 20% of all patients with NF1 will develop these tumours, typically in early childhood. Conversely, approximately one-third of pilocytic astrocytomas involving the optic nerves have associated NF1.

Clinical presentation

Presentation depends on location. In posterior fossa tumours, there is predominantly a mass effect with signs of raised intracranial pressure, especially when hydrocephalus is present. Bulbar symptoms or cerebellar symptoms may also be present.

Pathology

Location

By far the most common location is the cerebellum, with the optic pathway being the next most common, particularly in patients with neurofibromatosis type 1. In adults, most tumours are supratentorial 11.

The distribution within the cerebellum varies with many tumours involving both the vermis and the cerebellar hemisphere.

In general, pilocytic astrocytomas typically arise from midline structures.

  • cerebellum

    • 60%

  • optic pathway (optic nerve, optic chiasm, hypothalamus, optic radiation)

  • other less common locations

    • brainstem

    • cerebral hemispheres: more frequent in adults11

    • cerebral ventricles

    • velum interpositum

    • spinal cord: see spinal pilocytic astrocytoma

Microscopic appearance

The term pilocytic refers to the elongated hair-like projections from the neoplastic cells 4. The presence of eosinophilic Rosenthal fibres is a characteristic feature and hyalinization of blood vessels is also common. The histological features are, however, fairly heterogeneous even within the one tumour, with some areas mimicking diffuse astrocytomas and even oligodendrogliomas 6. 

Immunophenotype

Immunohistochemistry reflects astrocytic differentiation 6: 

Genetics

Pilocytic astrocytoma, as well as pleomorphic xanthoastrocytomas, frequently have BRAF alterations (present in ~70% of cases). Importantly they, along with other paediatric low-grade gliomas, lack IDH mutations and TP53 mutations 6,7. 

Radiographic features

General

Pilocytic astrocytomas range in appearance:

  • large cystic component with a brightly enhancing mural nodule: 67%

    • non-enhancing cyst wall: 21%

    • enhancing cyst wall: 46%

  • heterogeneous, mixed solid and multiple cysts and central necrosis: 16%

  • completely solid: 17%

Enhancement is almost invariably present (~95%). Up to 20% may demonstrate some calcification. Haemorrhage is an uncommon complication.

MRI

  • T1

    • solid component:iso- to hypointense compared to adjacent brain

    • cystic component: fluid signal unless haemorrhagic

  • T1 C+ (Gd)

    • vivid contrast enhancement

    • the cyst wall enhances in ~50% of cases

  • T2

    • solid component: hyperintense compared to adjacent brain 

    • cystic component: high signal

  • T2*/GRE/SWI: signal loss if calcification or haemorrhage present

Treatment and prognosis

They are slow-growing well-circumscribed tumours with an overall good prognosis following treatment (5-year and 10-year survival >95%) 6. Cystic tumours have an even better prognosis while fibrillary variants tend to do worse.

Surgical resection, if complete, is usually curative. Some surgeons advocate that only the nodule needs to be resected to achieve a cure, as the cyst walls are non-neoplastic, even if enhancing 2.

Adults have a poorer prognosis, with only 53% 5-year survival 11,12.

It is also worth noting that historically some patients with neurofibromatosis type 1 and high-grade cerebellar tumours diagnosed as pilocytic astrocytomas, actually represented high-grade astrocytoma with piloid features.

History and etymology

In 1931, Harvey Cushing was the first who described this tumour, based on his studies of 76 cases of cerebellar astrocytomas 5. Pilocytic means "hair-like" and is derived from the Latin word pilus for hair.

Differential diagnosis

General imaging differential considerations include:

  • -<p><strong>Pilocytic astrocytomas</strong>, also known as <strong>juvenile pilocytic astrocytomas</strong>, are <a href="/articles/astrocytic-tumours">circumscribed astrocytic gliomas</a> that tend to occur in young patients. They are considered WHO grade 1 tumours in the current <a href="/articles/who-classification-of-cns-tumours-1">WHO classification of CNS tumours</a> and correspondingly have a relatively good prognosis.</p><p>These tumours have a range of imaging appearances, with the majority presenting as a large cystic lesion with a brightly enhancing mural nodule. Calcification can be present in around one-fifth of cases.</p><p>The majority of pilocytic astrocytomas arise from the cerebellum. <a href="/articles/optic-pathway-glioma">Optic pathway gliomas</a> and <a href="/articles/spinal-pilocytic-astrocytoma">spinal cord pilocytic astrocytomas</a> are discussed separately. </p><p>The remainder of this article focuses on a general discussion of pilocytic astrocytomas, particularly those in the cerebellum. </p><h4>Epidemiology</h4><p>Pilocytic astrocytomas are tumours of young people, with 75% occurring in the first two decades of life, typically late in the first decade (9-10 years). There is no recognised gender predisposition.</p><p>Although they only account for 0.6-5.1% of all intracranial neoplasms (1.7-7% of all glial tumours), they are the most common primary brain tumour of childhood (15%) <sup>7</sup> and the second most common paediatric <a href="/articles/posterior-fossa-tumours" title="Posterior fossa tumours">posterior fossa tumour</a> (25-35%) after <a href="/articles/medulloblastoma" title="Medulloblastoma">medulloblastomas</a> <sup>10</sup>.</p><h5>Associations</h5><p>There is a strong association with <a href="/articles/neurofibromatosis-type-1">neurofibromatosis type 1 (NF1)</a>. NF1-associated tumours have a tendency to affect the optic nerves and chiasm (see: <a href="/articles/optic-pathway-glioma">optic pathway glioma</a>). The association between NF1 and pilocytic astrocytomas is so strong that up to 20% of all patients with NF1 will develop these tumours, typically in early childhood. Conversely, approximately one-third of pilocytic astrocytomas involving the optic nerves have associated NF1.</p><h4>Clinical presentation</h4><p>Presentation depends on location. In <a href="/articles/posterior-fossa-tumours">posterior fossa tumours</a>, there is predominantly a mass effect with signs of raised intracranial pressure, especially when hydrocephalus is present. Bulbar symptoms or cerebellar symptoms may also be present.</p><h4>Pathology</h4><h5>Location</h5><p>By far the most common location is the cerebellum, with the optic pathway being the next most common, particularly in patients with <a href="/articles/neurofibromatosis-type-1">neurofibromatosis type 1</a>. The distribution within the cerebellum varies with many tumours involving both the vermis and the cerebellar hemisphere.</p><p>In general, pilocytic astrocytomas typically arise from midline structures.</p><ul>
  • -<li>
  • -<p>cerebellum</p>
  • -<ul><li><p>60%</p></li></ul>
  • -</li>
  • -<li>
  • -<p>optic pathway (optic nerve, optic chiasm, hypothalamus, optic radiation)</p>
  • -<ul>
  • -<li><p>25-30%, particularly common in NF1</p></li>
  • -<li><p>see <a href="/articles/optic-pathway-glioma">optic pathway glioma</a></p></li>
  • -</ul>
  • -</li>
  • -<li>
  • -<p>other less common locations</p>
  • -<ul>
  • -<li><p>brainstem</p></li>
  • -<li><p>cerebral hemispheres: more frequent in adults</p></li>
  • -<li><p>cerebral ventricles</p></li>
  • -<li><p>velum interpositum</p></li>
  • -<li><p>spinal cord: see <a href="/articles/spinal-pilocytic-astrocytoma">spinal pilocytic astrocytoma</a></p></li>
  • -</ul>
  • -</li>
  • -</ul><h5>Microscopic appearance</h5><p>The term pilocytic refers to the elongated hair-like projections from the neoplastic cells <sup>4</sup>. The presence of eosinophilic <a href="/articles/rosenthal-fibres">Rosenthal fibres</a> is a characteristic feature and hyalinization of blood vessels is also common. The histological features are, however, fairly heterogeneous even within the one tumour, with some areas mimicking diffuse astrocytomas and even oligodendrogliomas <sup>6</sup>. </p><h5>Immunophenotype</h5><p><a href="/articles/immunohistochemistry">Immunohistochemistry</a> reflects astrocytic differentiation <sup>6</sup>: </p><ul>
  • -<li><p><a href="/articles/glial-fibrillary-acid-protein-gfap">GFAP</a>: positive</p></li>
  • -<li><p><a href="/articles/s100">S100</a>: positive</p></li>
  • -<li><p><a href="/articles/olig2">OLIG2</a>: positive</p></li>
  • -<li><p><a href="/articles/isocitrate-dehydrogenase">IDH R132H mutation</a>: negative</p></li>
  • -<li><p><a href="/articles/p53">p53 protein</a>: negative or weak</p></li>
  • -</ul><h5>Genetics</h5><p>Pilocytic astrocytoma, as well as <a href="/articles/pleomorphic-xanthoastrocytoma">pleomorphic xanthoastrocytomas</a>, frequently have <a href="/articles/braf-1"><em>BRAF</em></a> alterations (present in ~70% of cases). Importantly they, along with other paediatric low-grade gliomas, lack <a href="/articles/isocitrate-dehydrogenase">IDH mutations</a> and <a href="/articles/tp53-gene-1">TP53 mutations</a> <sup>6,7</sup>. </p><h4>Radiographic features</h4><h5>General</h5><p>Pilocytic astrocytomas range in appearance:</p><ul>
  • -<li>
  • -<p>large cystic component with a brightly enhancing mural nodule: 67%</p>
  • -<ul>
  • -<li><p>non-enhancing cyst wall: 21%</p></li>
  • -<li><p>enhancing cyst wall: 46%</p></li>
  • -</ul>
  • -</li>
  • -<li><p>heterogeneous, mixed solid and multiple cysts and central necrosis: 16%</p></li>
  • -<li><p>completely solid: 17%</p></li>
  • -</ul><p>Enhancement is almost invariably present (~95%). Up to 20% may demonstrate some calcification. Haemorrhage is an uncommon complication.</p><h5>MRI</h5><ul>
  • -<li>
  • -<p><strong>T1</strong></p>
  • -<ul>
  • -<li><p>solid component:<strong> </strong>iso- to hypointense compared to adjacent brain</p></li>
  • -<li><p>cystic component: fluid signal unless haemorrhagic</p></li>
  • -</ul>
  • -</li>
  • -<li>
  • -<p><strong>T1 C+ (Gd)</strong></p>
  • -<ul>
  • -<li><p>vivid contrast enhancement</p></li>
  • -<li><p>the cyst wall enhances in ~50% of cases</p></li>
  • -</ul>
  • -</li>
  • -<li>
  • -<p><strong>T2</strong></p>
  • -<ul>
  • -<li><p>solid component: hyperintense compared to adjacent brain </p></li>
  • -<li><p>cystic component: high signal</p></li>
  • -</ul>
  • -</li>
  • -<li><p><strong>T2*/GRE/SWI: </strong>signal loss if calcification or haemorrhage present</p></li>
  • -</ul><h4>Treatment and prognosis</h4><p>They are slow-growing well-circumscribed tumours with an overall good prognosis following treatment (5-year and 10-year survival &gt;95%) <sup>6</sup>. Cystic tumours have an even better prognosis while fibrillary variants tend to do worse.</p><p>Surgical resection, if complete, is usually curative. Some surgeons advocate that only the nodule needs to be resected to achieve a cure, as the cyst walls are non-neoplastic, even if enhancing <sup>2</sup>.</p><h4>History and etymology</h4><p>In 1931, <strong>Harvey Cushing</strong> was the first who described this tumour, based on his studies of 76 cases of cerebellar astrocytomas <sup>5</sup>. Pilocytic means "hair-like" and is derived from the Latin word pilus for hair.</p><h4>Differential diagnosis</h4><p>General imaging differential considerations include:</p><ul>
  • -<li>
  • -<p><a href="/articles/high-grade-astrocytoma-with-piloid-features-1">high-grade astrocytoma with piloid features</a></p>
  • -<ul>
  • -<li><p>particularly in adults and in patients with <a href="/articles/neurofibromatosis-type-1">neurofibromatosis type 1</a></p></li>
  • -<li><p>terrible prognosis</p></li>
  • -</ul>
  • -</li>
  • -<li>
  • -<p><a href="/articles/haemangioblastoma-central-nervous-system-2">haemangioblastoma</a></p>
  • -<ul>
  • -<li><p>usually seen in adults. In children, usually associated with <a href="/articles/von-hippel-lindau-disease-5">von Hippel-Lindau disease</a></p></li>
  • -<li><p>cyst wall usually does not enhance</p></li>
  • -<li><p>doesn't show calcifications</p></li>
  • -<li><p>smaller mural nodule with angiographic contrast blush</p></li>
  • -</ul>
  • -</li>
  • -<li>
  • -<p><a href="/articles/medulloblastoma">medulloblastoma</a></p>
  • -<ul>
  • -<li><p>typically arise from the midline (especially the vermis and roof of the fourth ventricle) rather than the cerebellar hemisphere</p></li>
  • -<li><p>usually seen in younger patients (2-6 years of age)</p></li>
  • -</ul>
  • -</li>
  • -<li>
  • -<p><a href="/articles/atypical-teratoidrhabdoid-tumour">atypical teratoid/rhabdoid tumour (AT/RT)</a></p>
  • -<ul><li><p>larger heterogeneously enhancing mass</p></li></ul>
  • -</li>
  • -<li>
  • -<p><a href="/articles/ependymoma">ependymoma</a></p>
  • -<ul>
  • -<li><p>tends to fill the <a href="/articles/fourth-ventricle">fourth ventricle</a> and protrude out of the <a href="/articles/lateral-apertures-of-luschka">foramen of Luschka</a> and <a href="/articles/median-aperture-of-magendie">foramina of Magendie</a></p></li>
  • -<li><p>large cystic component less common</p></li>
  • -</ul>
  • -</li>
  • -<li><p><a href="/articles/ganglioglioma">ganglioglioma</a></p></li>
  • -<li><p><a href="/articles/pleomorphic-xanthoastrocytoma">pleomorphic xanthoastrocytoma (PXA)</a></p></li>
  • -<li><p><a href="/articles/cerebellar-haemorrhage">cerebellar haemorrhage</a></p></li>
  • +<p><strong>Pilocytic astrocytomas</strong>, also known as <strong>juvenile pilocytic astrocytomas</strong>, are <a href="/articles/astrocytic-tumours">circumscribed astrocytic gliomas</a> that typically to occur in young patients. The majority of sporadic pilocytic astrocytomas arise from the cerebellum, whereas in the setting of <a href="/articles/neurofibromatosis-type-1" title="Neurofibromatosis type 1">neurofibromatosis type 1</a>, they often involve the optic chiasm and pathway. In adults, they are typically supratentorial <sup>11</sup>. </p><p>Pilocytic astrocytomas are considered WHO grade 1 tumours in the current <a href="/articles/who-classification-of-cns-tumours-1">WHO classification of CNS tumours</a> and correspondingly have a relatively good prognosis.</p><p>These tumours have a range of imaging appearances, with the majority presenting as a large cystic lesion with a brightly enhancing mural nodule. Calcification can be present in around one-fifth of cases.</p><p><a href="/articles/optic-pathway-glioma">Optic pathway gliomas</a> and <a href="/articles/spinal-pilocytic-astrocytoma">spinal cord pilocytic astrocytomas</a> are discussed separately. The remainder of this article focuses on a general discussion of pilocytic astrocytomas, particularly those in the cerebellum. </p><h4>Epidemiology</h4><p>Pilocytic astrocytomas are tumours of young people, with 69% occurring in the first two decades of life, typically late in the first decade (9-10 years) <sup>11</sup>. They do, however, also occasionally arise in adults <sup>11</sup>. </p><p>Although they only account for 0.6-5.1% of all intracranial neoplasms (1.7-7% of all glial tumours), they are the most common primary brain tumour of childhood (15%) <sup>7</sup> and the second most common paediatric <a href="/articles/posterior-fossa-tumours" title="Posterior fossa tumours">posterior fossa tumour</a> (25-35%) after <a href="/articles/medulloblastoma" title="Medulloblastoma">medulloblastomas</a> <sup>10</sup>.</p><h5>Associations</h5><p>There is a strong association with <a href="/articles/neurofibromatosis-type-1">neurofibromatosis type 1 (NF1)</a>. NF1-associated tumours have a tendency to affect the optic nerves and chiasm (see: <a href="/articles/optic-pathway-glioma">optic pathway glioma</a>). The association between NF1 and pilocytic astrocytomas is so strong that up to 20% of all patients with NF1 will develop these tumours, typically in early childhood. Conversely, approximately one-third of pilocytic astrocytomas involving the optic nerves have associated NF1.</p><h4>Clinical presentation</h4><p>Presentation depends on location. In <a href="/articles/posterior-fossa-tumours">posterior fossa tumours</a>, there is predominantly a mass effect with signs of raised intracranial pressure, especially when hydrocephalus is present. Bulbar symptoms or cerebellar symptoms may also be present.</p><h4>Pathology</h4><h5>Location</h5><p>By far the most common location is the cerebellum, with the optic pathway being the next most common, particularly in patients with <a href="/articles/neurofibromatosis-type-1">neurofibromatosis type 1</a>. In adults, most tumours are supratentorial <sup>11</sup>. </p><p>The distribution within the cerebellum varies with many tumours involving both the vermis and the cerebellar hemisphere.</p><p>In general, pilocytic astrocytomas typically arise from midline structures.</p><ul>
  • +<li>
  • +<p>cerebellum</p>
  • +<ul><li><p>60%</p></li></ul>
  • +</li>
  • +<li>
  • +<p>optic pathway (optic nerve, optic chiasm, hypothalamus, optic radiation)</p>
  • +<ul>
  • +<li><p>25-30%, particularly common in NF1</p></li>
  • +<li><p>see <a href="/articles/optic-pathway-glioma">optic pathway glioma</a></p></li>
  • +</ul>
  • +</li>
  • +<li>
  • +<p>other less common locations</p>
  • +<ul>
  • +<li><p>brainstem</p></li>
  • +<li><p>cerebral hemispheres: more frequent in adults <sup>11</sup></p></li>
  • +<li><p>cerebral ventricles</p></li>
  • +<li><p>velum interpositum</p></li>
  • +<li><p>spinal cord: see <a href="/articles/spinal-pilocytic-astrocytoma">spinal pilocytic astrocytoma</a></p></li>
  • +</ul>
  • +</li>
  • +</ul><h5>Microscopic appearance</h5><p>The term pilocytic refers to the elongated hair-like projections from the neoplastic cells <sup>4</sup>. The presence of eosinophilic <a href="/articles/rosenthal-fibres">Rosenthal fibres</a> is a characteristic feature and hyalinization of blood vessels is also common. The histological features are, however, fairly heterogeneous even within the one tumour, with some areas mimicking diffuse astrocytomas and even oligodendrogliomas <sup>6</sup>. </p><h5>Immunophenotype</h5><p><a href="/articles/immunohistochemistry">Immunohistochemistry</a> reflects astrocytic differentiation <sup>6</sup>: </p><ul>
  • +<li><p><a href="/articles/glial-fibrillary-acid-protein-gfap">GFAP</a>: positive</p></li>
  • +<li><p><a href="/articles/s100">S100</a>: positive</p></li>
  • +<li><p><a href="/articles/olig2">OLIG2</a>: positive</p></li>
  • +<li><p><a href="/articles/isocitrate-dehydrogenase">IDH R132H mutation</a>: negative</p></li>
  • +<li><p><a href="/articles/p53">p53 protein</a>: negative or weak</p></li>
  • +</ul><h5>Genetics</h5><p>Pilocytic astrocytoma, as well as <a href="/articles/pleomorphic-xanthoastrocytoma">pleomorphic xanthoastrocytomas</a>, frequently have <a href="/articles/braf-1"><em>BRAF</em></a> alterations (present in ~70% of cases). Importantly they, along with other paediatric low-grade gliomas, lack <a href="/articles/isocitrate-dehydrogenase">IDH mutations</a> and <a href="/articles/tp53-gene-1">TP53 mutations</a> <sup>6,7</sup>. </p><h4>Radiographic features</h4><h5>General</h5><p>Pilocytic astrocytomas range in appearance:</p><ul>
  • +<li>
  • +<p>large cystic component with a brightly enhancing mural nodule: 67%</p>
  • +<ul>
  • +<li><p>non-enhancing cyst wall: 21%</p></li>
  • +<li><p>enhancing cyst wall: 46%</p></li>
  • +</ul>
  • +</li>
  • +<li><p>heterogeneous, mixed solid and multiple cysts and central necrosis: 16%</p></li>
  • +<li><p>completely solid: 17%</p></li>
  • +</ul><p>Enhancement is almost invariably present (~95%). Up to 20% may demonstrate some calcification. Haemorrhage is an uncommon complication.</p><h5>MRI</h5><ul>
  • +<li>
  • +<p><strong>T1</strong></p>
  • +<ul>
  • +<li><p>solid component:<strong> </strong>iso- to hypointense compared to adjacent brain</p></li>
  • +<li><p>cystic component: fluid signal unless haemorrhagic</p></li>
  • +</ul>
  • +</li>
  • +<li>
  • +<p><strong>T1 C+ (Gd)</strong></p>
  • +<ul>
  • +<li><p>vivid contrast enhancement</p></li>
  • +<li><p>the cyst wall enhances in ~50% of cases</p></li>
  • +</ul>
  • +</li>
  • +<li>
  • +<p><strong>T2</strong></p>
  • +<ul>
  • +<li><p>solid component: hyperintense compared to adjacent brain </p></li>
  • +<li><p>cystic component: high signal</p></li>
  • +</ul>
  • +</li>
  • +<li><p><strong>T2*/GRE/SWI: </strong>signal loss if calcification or haemorrhage present</p></li>
  • +</ul><h4>Treatment and prognosis</h4><p>They are slow-growing well-circumscribed tumours with an overall good prognosis following treatment (5-year and 10-year survival &gt;95%) <sup>6</sup>. Cystic tumours have an even better prognosis while fibrillary variants tend to do worse.</p><p>Surgical resection, if complete, is usually curative. Some surgeons advocate that only the nodule needs to be resected to achieve a cure, as the cyst walls are non-neoplastic, even if enhancing <sup>2</sup>.</p><p>Adults have a poorer prognosis, with only 53% 5-year survival <sup>11,12</sup>. </p><p>It is also worth noting that historically some patients with neurofibromatosis type 1 and high-grade cerebellar tumours diagnosed as pilocytic astrocytomas, actually represented <a href="/articles/high-grade-astrocytoma-with-piloid-features-1" title="High-grade astrocytoma with piloid features">high-grade astrocytoma with piloid features</a>. </p><h4>History and etymology</h4><p>In 1931, <strong>Harvey Cushing</strong> was the first who described this tumour, based on his studies of 76 cases of cerebellar astrocytomas <sup>5</sup>. Pilocytic means "hair-like" and is derived from the Latin word pilus for hair.</p><h4>Differential diagnosis</h4><p>General imaging differential considerations include:</p><ul>
  • +<li>
  • +<p><a href="/articles/high-grade-astrocytoma-with-piloid-features-1">high-grade astrocytoma with piloid features</a></p>
  • +<ul>
  • +<li><p>particularly in adults and in patients with <a href="/articles/neurofibromatosis-type-1">neurofibromatosis type 1</a></p></li>
  • +<li><p>terrible prognosis</p></li>
  • +</ul>
  • +</li>
  • +<li>
  • +<p><a href="/articles/haemangioblastoma-central-nervous-system-2">haemangioblastoma</a></p>
  • +<ul>
  • +<li><p>usually seen in adults. In children, usually associated with <a href="/articles/von-hippel-lindau-disease-5">von Hippel-Lindau disease</a></p></li>
  • +<li><p>cyst wall usually does not enhance</p></li>
  • +<li><p>doesn't show calcifications</p></li>
  • +<li><p>smaller mural nodule with angiographic contrast blush</p></li>
  • +</ul>
  • +</li>
  • +<li>
  • +<p><a href="/articles/medulloblastoma">medulloblastoma</a></p>
  • +<ul>
  • +<li><p>typically arise from the midline (especially the vermis and roof of the fourth ventricle) rather than the cerebellar hemisphere</p></li>
  • +<li><p>usually seen in younger patients (2-6 years of age)</p></li>
  • +</ul>
  • +</li>
  • +<li>
  • +<p><a href="/articles/atypical-teratoidrhabdoid-tumour">atypical teratoid/rhabdoid tumour (AT/RT)</a></p>
  • +<ul><li><p>larger heterogeneously enhancing mass</p></li></ul>
  • +</li>
  • +<li>
  • +<p><a href="/articles/ependymoma">ependymoma</a></p>
  • +<ul>
  • +<li><p>tends to fill the <a href="/articles/fourth-ventricle">fourth ventricle</a> and protrude out of the <a href="/articles/lateral-apertures-of-luschka">foramen of Luschka</a> and <a href="/articles/median-aperture-of-magendie">foramina of Magendie</a></p></li>
  • +<li><p>large cystic component less common</p></li>
  • +</ul>
  • +</li>
  • +<li><p><a href="/articles/ganglioglioma">ganglioglioma</a></p></li>
  • +<li><p><a href="/articles/pleomorphic-xanthoastrocytoma">pleomorphic xanthoastrocytoma (PXA)</a></p></li>
  • +<li><p><a href="/articles/cerebellar-haemorrhage">cerebellar haemorrhage</a></p></li>

References changed:

  • 11. Theeler B, Ellezam B, Sadighi Z et al. Adult Pilocytic Astrocytomas: Clinical Features and Molecular Analysis. Neuro Oncol. 2014;16(6):841-7. <a href="https://doi.org/10.1093/neuonc/not246">doi:10.1093/neuonc/not246</a> - <a href="https://www.ncbi.nlm.nih.gov/pubmed/24470550">Pubmed</a>
  • 12. Johnson D, Brown P, Galanis E, Hammack J. Pilocytic Astrocytoma Survival in Adults: Analysis of the Surveillance, Epidemiology, and End Results Program of the National Cancer Institute. J Neurooncol. 2012;108(1):187-93. <a href="https://doi.org/10.1007/s11060-012-0829-0">doi:10.1007/s11060-012-0829-0</a> - <a href="https://www.ncbi.nlm.nih.gov/pubmed/22367412">Pubmed</a>

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