General
- Used to be called CNS Neuroblastoma
Definition
- Essential:
- An embryonal tumour with foci of neuroblastic or neuronal differentiation AND
- Activation of FOXR2 by structural rearrangement and gene fusion OR (for unresolved lesions)
- A DNA methylation profile aligned with CNS neuroblastoma, F0XR2-activated
Number
- Usually occur in childhood
- A slight female preponderance
Location
- Common
- Cerebral hemisphere
- Rare
- Intraventricular
Pathology
- Macro
- Typically well circumscribed pink masses.
- They are soft, unless they contain a prominent desmoplastic component, in which case they are firm and often have a tan colour.
- Micro
- Poorly differentiated cells with a high N:C ratio;
- Round, oval, or angulated hyperchromatic nuclei; and abundant mitotic activity
- Areas of necrosis are common
- Palisades of embryonal cells and Homer Wright (neuroblastic) rosettes may be evident.
Genetics
- Complex interchromosomal and intrachromosomal rearrangements converging on the transcription factor gene FOXR2, producing a fusion between the entire FOXR2 gene and different gene partners
- FOXR2
- A forkhead transcription factor
- Located on the Xp11.21 chromosome
- Expression is normally restricted to the testis
- No idea of the mechanism of action of FOXR2 in cancer formation yet
Radiology
- Imaging features
- A large supratentorial mass
- Mixed solid and cystic components
- Restricted diffusion
- Enhancement is variable
- Showed relatively little mass effect despite their large size
- Sharply defined peripheral contour
- Central necrosis
- Moderate amount of perilesional oedema.
Images
- A 5-year-old girl.
- Methylation class, CNS neuroblastoma with FOXR2 activation.
- T2w (A) and FLAIR (B) show a large, circumscribed mass centred on the left striatocapsular region with inferior extension into the suprasellar cistern.
- The tumour is effacing the third ventricle and the lateral ventricles are dilated.
- There is marked restricted diffusion (C) and heterogeneous enhancement on T1-CE (D)
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