Atypical teratoid/rhabdoid tumour
Updates to Article Attributes
Atypical teratoid/rhabdoid tumours (AT/RTs) are an uncommon WHO Grade IV tumour, which in in the vast majority of cases occurs in young children less than two years of age. It most frequently presents as a posterior fossa mass.
AT/RTs were until relatively recently classed as medulloblastomas, although both clinically and histologically they are different entities.
Epidemiology
They present in young children (median age is less than 2-3 years 2), whereas medulloblastomas typically occur in mid childhood (median age 6 years).
Pathology
Rhabdoid cells are the hallmark of AT/RT which however make up only a tiny fraction of the tumour, which is otherwise indistinguishable on imaging and histology from a medulloblastoma or supratentorialPNET. However, almost all AT/RTs show loss loss of INI1 tumour suppressor gene on chromosome 22 which distinguishes them from other entities 8.
Markers
Relatively specific markers include:
- epithelial membrane antigen
- vimentin
- smooth muscle actin
Location
- infratentorial: ~50%
- cerebellum (most common)
- brainstem
- supratentorial
- cerebral hemispheres
- pineal gland region (see pineal mass differential diagnosis)
- septum pellucidum
- hypothalamus
Radiographic features
CT brain
- often isodense to gray matter
- may demonstrate heterogeneous enhancement
- calcification is common
- may show associated obstructive hydrocephalus
MRI brain
Can show necrosis necrosis, multiple foci of cyst formation and sometimes haemorrhage sometimes haemorrhage:
- T1: iso- to slightly hyperintense to grey matter(haemorrhagic areas can be more hyperintense)
- T2: generally hyperintense (haemorrhagic areas can be hypointense)
- T1 C+ (Gd): heterogeneous enhancement
-
MR spectroscopy
- Cho: elevated
- NAA: decreased
Treatment and prognosis
Surgery with debulking can be offered in some cases. Tumours can demonstrate leptomeningeal dissemination. Clinically AT/RTs have much poorer prognosis than medulloblastomas, with little if any response to chemotherapy, and death usually occuring within a year of diagnosis.
Differential diagnosis
Imaging differenial considerations include:
- supratentorial CNS PNET: particularly for supretentorial ATRT's
- medulloblastoma: tends to occur in an older age group 6
- intracranial teratoma
-<p><strong>Atypical teratoid/rhabdoid tumours</strong> <strong>(AT/RTs)</strong> are an uncommon <a href="/articles/cns-tumours-classification-and-grading-who">WHO Grade IV</a> tumour, which in the vast majority of cases occurs in young children less than two years of age. It most frequently presents as a <a href="/articles/posterior-fossa-tumours">posterior fossa mass</a>. </p><p>AT/RTs were until relatively recently classed as <a href="/articles/medulloblastoma">medulloblastomas</a>, although both clinically and histologically they are different entities.</p><h4>Epidemiology</h4><p>They present in young children (median age is less than 2-3 years <sup>2</sup>), whereas medulloblastomas typically occur in mid childhood (median age 6 years).</p><h4>Pathology</h4><p>Rhabdoid cells are the hallmark of AT/RT which however make up only a tiny fraction of the tumour, which is otherwise indistinguishable on imaging and histology from a medulloblastoma or supratentorial <a href="/articles/primitive-neuroectodermal-tumour-of-the-cns">PNET</a>. However, almost all AT/RTs show loss of INI1 tumour suppressor gene on chromosome 22 which distinguishes them from other entities <sup>8</sup>.</p><h5>Markers</h5><p>Relatively specific markers include:</p><ul>- +<p><strong>Atypical teratoid/rhabdoid tumours</strong> <strong>(AT/RTs)</strong> are an uncommon <a href="/articles/cns-tumours-classification-and-grading-who">WHO Grade IV</a> tumour, which in the vast majority of cases occurs in young children less than two years of age. It most frequently presents as a <a href="/articles/posterior-fossa-tumours">posterior fossa mass</a>. </p><p>AT/RTs were until relatively recently classed as <a href="/articles/medulloblastoma">medulloblastomas</a>, although both clinically and histologically they are different entities.</p><h4>Epidemiology</h4><p>They present in young children (median age is less than 2-3 years <sup>2</sup>), whereas medulloblastomas typically occur in mid childhood (median age 6 years).</p><h4>Pathology</h4><p>Rhabdoid cells are the hallmark of AT/RT which however make up only a tiny fraction of the tumour, which is otherwise indistinguishable on imaging and histology from a medulloblastoma or supratentorial <a href="/articles/primitive-neuroectodermal-tumour-of-the-cns">PNET</a>. However, almost all AT/RTs show loss of INI1 tumour suppressor gene on chromosome 22 which distinguishes them from other entities <sup>8</sup>.</p><h5>Markers</h5><p>Relatively specific markers include:</p><ul>
-</ul><h4>Radiographic features</h4><h5>CT brain</h5><ul>- +</ul><h4>Radiographic features</h4><h5>CT</h5><ul>
-</ul><h5>MRI brain</h5><p>Can show necrosis, multiple foci of cyst formation and sometimes haemorrhage:</p><ul>- +</ul><h5>MRI</h5><p>Can show necrosis, multiple foci of cyst formation and sometimes haemorrhage:</p><ul>
-<strong>T1:</strong> iso- to slightly hyperintense to grey matter (haemorrhagic areas can be more hyperintense)</li>- +<strong>T1:</strong> iso- to slightly hyperintense to grey matter (haemorrhagic areas can be more hyperintense)</li>
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