Atypical teratoid rhabdoid tumour (prenatal US and neonatal MRI)
Presentation
Uncomplicated standard singleton pregnancy with regular clinical and US follow-up. Physiological delivery at 38WG. At day 1, generalised hypotonia, lack of succion upon breastfeeding.
Patient Data
US standard screening until...
US standard screening until 35WG posterior fossa & cerebellum assessment
Normal posterior fossa scans at 26WG,32WG and 35WG. Cerebellum biometry and morphology were normal. Sylvian fissure were as according to term, normal cavum.
D1 CT after transfont...
D1 CT after transfontanellar echography showing hydrocephalus
Midline, vermis centred posterior fossa tumour bulging into the 4th ventricle, with obstructive hydrocephalus.
Tumour is heterogeneous, with cystic CSF-like densities and spontaneous haemorrhage. No internal calcification.
Round shape, no spreading through the foramen of Magendie nor the lateral foramens of Luschka.
MR at Day 1 after CT
Midline, vermis centred posterior fossa tumour bulging into the 4th ventricle, with obstructive hydrocephalus. Haemorrhage within the occipital horns of lateral ventricles due to external ventricular drains.
Tumour is heterogeneous, with cystic CSF-like densities and spontaneous haemorrhage well seen on T2*. DWI is non-contributing due to haemorrhage. No internal calcification on CT.
Round shape, no spreading through the foramen of Magendie nor the lateral foramens of Luschka.
Peripheral enhancement.
Case Discussion
This is a case of a rapidly progressive posterior fossa tumour diagnosed on day 1 in a term newborn, which narrows down the list of possible diagnoses by a long way. Molecular genetics on pathology were typical of an atypical teratoid rhabdoid tumour.
As always in tumours, the location and age at diagnosis are key features. Posterior fossa tumours in children usually lead to possible diagnoses:
- pilocytic astrocytoma
- ependymoma
- medulloblastoma
AT/RT stands for atypical teratoid rhabdoid tumour. It mimics medulloblastoma with its round shape and midline location. However, medulloblastoma are usually found in older children around 10 years of age, with high cellularity, DWI restriction, and is rarely haemorrhagic and heterogeneous. On the other hand, AT/RT is almost exclusively found in newborns and neonates up to 2 years of age and is frequently heterogeneous. Tumour progression is rapid, as expected from embryonal malignant tumours, and the prognosis is poor. This tumour is associated with rhabdoid tumour predisposition syndrome, a genetic autosomal dominant condition which is in most cases de novo.
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