Astroblastoma, MN1-altered
Updates to Article Attributes
Astroblastomas are uncommon primary neuroepithelialrare glial tumours which, along with choroid gliomasusually found in the cerebral hemispheres of the third ventricleyoung adults and angiocentric gliomas, are grouped as other neuroepithelial tumours in the 2007 version of the WHO classification of CNS tumours
Epidemiology
They occur at all ages range from early childhood to 6th decade but are most commonly seen in children, adolescents, and young adults with a mean age between 10-30 years 2,5. Their incidence is estimated to be 0.45-2.8% of all neuroglial tumours A female predilection has been suggested in some reports 45.
Pathology
Astroblastomas, along with choroid gliomas of the third ventricle and angiocentric gliomas, are grouped as other neuroepithelial tumours in the current (2016) version of the WHO classification of CNS tumours5.
They have not yet been given a WHO grade, but do have a range of histological appearance and biological behaviour ranging from relatively indolent (astroblastoma) to aggressive (anaplastic or malignant astroblastoma) 4,5.
Macroscopic appearance
They are well-demarcated masses with areas of cystic degeneration and necrosis giving it a bubbly appearance. Haemorrhage and adjacent brain infiltration are rare.
Microscopic appearance
Two distinct histological types were reported 4:
-
low-grade type: well differentiated patternAstroblastomas have elongated glial cells with abundant eosinophilic cytoplasm andfavourable prognosis high-grade type: more anaplastic features with short postoperative survival
Histology
A common histologic finding is perivascular rosettes similara broad, or “stout”, GFAP positive process extending radially towards a central blood vessel, forming "astroblastic pseudorosettes", reminiscent to the perivascular pseudorosettes of ependymomas, which are a characteristic feature of this tumour. The central vessel tends to be hyalinized.
Although no agreed-upon criteria have been accepted, anaplastic/malignant histological features include 5:
- increased mitotic activity (>5 mitoses per 10 high-powered fields)
- high cellularity
- anaplastic nuclear features
- microvascular proliferation
- palisading necrosis
- usually Ki-67 >10%
Location Immunophenotype
Almost always supratentorial and peripheral.
Radiographic features
TheyAstroblastomas are largeusually fairly sizable, peripherally located, supratentorial lobulated solid cystic masses with little if any associated vasogenic oedema1-5. Multiple cysts are common and can give it a bubbly appearance. Calcification is very common and seen in 85% of cases, and usually in a punctate pattern.
MRI
- T1: iso- to hypointense
- T2/FLAIR: heterogeneously hyperintense
- T1 Gd (C+): heterogeneous enhancement
Treatment and prognosis
Surgical resection is the treatment of choice with adjuvant radiation therapy and chemotherapy reserved for high-grade lesions. Unless being a high grade lesion recurrenceRecurrence after complete surgical resection of low-grade tumours is uncommon 4. Metastasis is also very rare.
Differential diagnosis
Possible imaging differential considerations include:
- supratentorial ependymoma
- atypical teratoid/rhabdoid tumour
- astrocytoma, particularly GBM or gemistocytic
-
oligodendroglioma
- nodular calcifications instead of punctate calcifications 2
- pleomorphic xanthoastrocytoma
dysembryoplastic neuroepithelial tumour (DNET)
-<p><strong>Astroblastomas are</strong> uncommon primary neuroepithelial tumours which, along with <a href="/articles/choroid-glioma-of-the-third-ventricle">choroid gliomas of the third ventricle</a> and <a href="/articles/angiocentric-glioma">angiocentric gliomas</a>, are grouped as <a href="/articles/who-classification-of-cns-tumours-1">other neuroepithelial tumours</a> in the 2007 version of the <a href="/articles/who-classification-of-cns-tumours-1">WHO classification of </a><a href="/articles/who-classification-of-cns-tumours-1">CNS tumours</a>.</p><h4>Epidemiology</h4><p>They occur at all ages range from early childhood to 6th decade but are most commonly seen in children, adolescents, and young adults with a mean age between 10-30 years <sup>2</sup>. Their incidence is estimated to be 0.45-2.8% of all neuroglial tumours <sup>4</sup>.</p><h4>Pathology</h4><p>They are well-demarcated masses with areas of cystic degeneration and necrosis giving it a bubbly appearance. Haemorrhage and adjacent brain infiltration are rare.</p><p>Two distinct histological types were reported <sup>4</sup>:</p><ul>-<li>low-grade type: well differentiated pattern and favourable prognosis</li>-<li>high-grade type: more anaplastic features with short postoperative survival</li>-</ul><h5>Histology</h5><p>A common histologic finding is perivascular rosettes similar to the <a href="/articles/ependymoma">ependymomas</a>.</p><h5>Location </h5><p>Almost always supratentorial and peripheral.</p><h4>Radiographic features</h4><p>They are large, peripherally located, supratentorial lobulated solid cystic masses with little if any associated vasogenic oedema. Multiple cysts give it a bubbly appearance. Calcification is very common and seen in 85% of cases, and usually in a punctate pattern.</p><h5>MRI</h5><ul>- +<p><strong>Astroblastomas are</strong> rare glial tumours usually found in the cerebral hemispheres of young adults and children. </p><h4>Epidemiology</h4><p>They occur at all ages range from early childhood to 6th decade but are most commonly seen in children, adolescents, and young adults with a mean age between 10-30 years <sup>2,5</sup>. A female predilection has been suggested in some reports <sup>5</sup>. </p><h4>Pathology</h4><p>Astroblastomas, along with <a href="/articles/chordoid-glioma-of-the-third-ventricle">choroid gliomas of the third ventricle</a> and <a href="/articles/angiocentric-glioma">angiocentric gliomas</a>, are grouped as <a href="/articles/who-classification-of-cns-tumours-1">other neuroepithelial tumours</a> in the current (2016) version of the <a href="/articles/who-classification-of-cns-tumours-1">WHO classification of </a><a href="/articles/who-classification-of-cns-tumours-1">CNS tumours</a> <sup>5</sup>.</p><p>They have not yet been given a WHO grade, but do have a range of histological appearance and biological behaviour ranging from relatively indolent (astroblastoma) to aggressive (anaplastic or malignant astroblastoma) <sup>4,5</sup>. </p><h5>Macroscopic appearance</h5><p>They are well-demarcated masses with areas of cystic degeneration and necrosis giving it a bubbly appearance. Haemorrhage and adjacent brain infiltration are rare.</p><h5>Microscopic appearance</h5><p>Astroblastomas have elongated glial cells with abundant eosinophilic cytoplasm and a broad, or “stout”, <a href="/articles/glial-fibrillary-acid-protein-gfap">GFAP</a> positive process extending radially towards a central blood vessel, forming "astroblastic pseudorosettes", reminiscent to the <a href="/articles/perivascular-pseudorosettes-ependymoma">perivascular pseudorosettes</a> of <a href="/articles/ependymoma">ependymomas</a>, which are a characteristic feature of this tumour. The central vessel tends to be hyalinized. </p><p>Although no agreed-upon criteria have been accepted, anaplastic/malignant histological features include <sup>5</sup>: </p><ul>
- +<li>increased mitotic activity (>5 mitoses per 10 high-powered fields)</li>
- +<li>high cellularity </li>
- +<li>anaplastic nuclear features</li>
- +<li>microvascular proliferation</li>
- +<li>palisading necrosis </li>
- +<li>usually Ki-67 >10%</li>
- +</ul><h5>Immunophenotype</h5><ul>
- +<li>
- +<a href="/articles/glial-fibrillary-acid-protein-gfap">GFAP</a>: positive</li>
- +<li>
- +<a href="/articles/s100">S100</a>: positive</li>
- +<li>
- +<a title="Vimentin" href="/articles/vimentin">vimentin</a>: positive</li>
- +<li>
- +<a href="/articles/epithelial-membrane-antigen-ema">EMA</a> (cell membrane): variable</li>
- +</ul><h4>Radiographic features</h4><p>Astroblastomas are usually fairly sizable, peripherally located, supratentorial lobulated solid cystic masses with little if any associated vasogenic oedema <sup>1-5</sup>. Multiple cysts are common and can give it a bubbly appearance. Calcification is very common and seen in 85% of cases, and usually in a punctate pattern.</p><h5>MRI</h5><ul>
-</ul><h4>Treatment and prognosis</h4><p>Surgical resection is the treatment of choice with adjuvant radiation therapy and chemotherapy reserved for high-grade lesions. Unless being a high grade lesion recurrence after surgical resection is uncommon <sup>4</sup>. Metastasis is also very rare.</p><h4>Differential diagnosis</h4><p>Possible imaging differential considerations include:</p><ul>-<li><a href="/articles/ependymoma">hemispheric ependymoma</a></li>- +</ul><h4>Treatment and prognosis</h4><p>Surgical resection is the treatment of choice with adjuvant radiation therapy and chemotherapy reserved for high-grade lesions. Recurrence after complete surgical resection of low-grade tumours is uncommon <sup>4</sup>. </p><h4>Differential diagnosis</h4><p>Possible imaging differential considerations include:</p><ul>
- +<li><a href="/articles/supratentorial-ependymoma">supratentorial ependymoma</a></li>
- +<a href="/articles/astrocytic-tumours">astrocytoma</a>, particularly <a href="/articles/glioblastoma">GBM</a> or <a href="/articles/gemistocytic-astrocytoma">gemistocytic</a>
- +</li>
- +<li>
-<li><a href="/articles/dysembryoplastic-neuroepithelial-tumour">dysembryoplastic neuroepithelial tumour (DNET)</a></li>
References changed:
- 5. Louis DN, Ohgaki H, Wiestler OD, Cavenee WK "WHO Classification of Tumours of the Central Nervous System. 4th Edition Revised" <a href="https://books.google.co.uk/books?vid=ISBN9789283244929">ISBN: 9789283244929</a><span class="ref_v4"></span>
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