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Paediatric neuro-oncology · Clinically reviewed

ATRT, a rare aggressive brain tumour in infants and young children.

A frightening diagnosis with rapidly improving science. Modern UK care combines specialist surgery, molecular subtyping, high-dose chemotherapy, proton beam therapy and family genetics.

Jump to treatment
A radiographer guides a patient onto the bed of an advanced 3 Tesla MRI scanner in a London imaging suite

Why trust this guide

  • 01

    Clinically reviewed

    Written by our editorial team and reviewed by a registered UK clinician before publication.

  • 02

    Sourced from guidance

    Checked against WHO 2021 CNS classification, EU-RHAB, ACNS0333, SIOPE and NHS specialist paediatric neuro-oncology guidance.

  • 03

    Current for 2026

    Reflects modern UK paediatric practice including molecular subtyping, proton beam therapy and germline SMARCB1 counselling.

Key facts

ATRT at a glance.

The essentials for parents and carers, in plain English. What ATRT is, who it affects, and how modern UK treatment approaches it.

  • What it is

    An atypical teratoid/rhabdoid tumour (ATRT) is a highly aggressive WHO grade 4 embryonal tumour of the central nervous system, almost always in infants and young children.

  • Who it affects

    Predominantly infants and children under 5 (median age around 2 years). Accounts for 1 to 2 per cent of paediatric brain tumours, but up to 20 per cent of CNS tumours in infants under 1.

  • Where it sits

    Roughly 50 per cent supratentorial and 50 per cent infratentorial (cerebellum, brainstem, posterior fossa). Around 15 to 30 per cent have leptomeningeal spread at diagnosis.

  • Molecular hallmark

    Biallelic inactivation of SMARCB1 (INI1/BAF47) in about 95 per cent; SMARCA4 loss in a small minority. A germline SMARCB1 mutation is found in around 35 per cent.

  • WHO 2021 subtypes

    Three molecular groups: ATRT-TYR (tyrosinase, younger, better outlook), ATRT-SHH (sonic hedgehog) and ATRT-MYC (older, often supratentorial, poorest prognosis).

  • Prognosis today

    Historically very poor, but 5-year survival on modern multimodal protocols is 25 to 45 per cent overall and up to 70 per cent for ATRT-TYR with complete resection and no metastases.

Why this guide matters

A rare tumour, a very specialist plan.

ATRT is uncommon, which is why care must be concentrated in specialist paediatric neuro-oncology centres. Three ideas shape everything that follows.

  • Molecular subtype changes the plan

    The WHO 2021 subtypes (TYR, SHH, MYC) carry different biology and prognosis, and increasingly shape trial choice and radiation decisions.

  • Radiation-sparing matters in infants

    For babies under 12 to 18 months, delayed or avoided radiotherapy protects the developing brain. Proton beam therapy is preferred when radiation is needed.

  • Genetics affects the whole family

    A germline SMARCB1 change is found in about a third of children. Cascade testing and surveillance can change outcomes for siblings and future pregnancies.

How the diagnosis is made

From first scan to a molecular diagnosis.

The steps a UK paediatric neuro-oncology team will typically follow, in order, so parents know what each investigation is for.

  1. 01

    Imaging and surgery

    Urgent MRI brain and whole spine

    Gadolinium-enhanced MRI of the brain and the entire spine is essential. Spinal seeding is common and changes staging and treatment.

  2. 02

    Imaging and surgery

    Neurosurgical biopsy and resection

    Tissue is obtained at the same operation as maximum safe resection. Frozen section guides intraoperative decisions.

  3. 03

    Imaging and surgery

    INI1 immunohistochemistry

    Loss of nuclear INI1 (SMARCB1) staining in tumour cells is diagnostic. FISH or sequencing confirms SMARCB1 deletion or mutation.

  4. 04

    Subtype and staging

    Molecular subtyping

    Methylation profiling and RNA analysis place the tumour into ATRT-TYR, ATRT-SHH or ATRT-MYC, which shapes prognosis and trial eligibility.

  5. 05

    Subtype and staging

    CSF cytology and staging

    Lumbar cerebrospinal fluid sampling (once safe) plus staging imaging completes the picture of local and metastatic disease.

  6. 06

    Genetics and baseline

    Germline SMARCB1 and SMARCA4 testing

    Every child is offered germline testing with genetic counselling. A germline change signals rhabdoid tumour predisposition syndrome (RTPS) and family implications.

  7. 07

    Genetics and baseline

    Baseline organ and sensory work-up

    Ophthalmology, audiology, endocrine bloods, echocardiogram, renal function, fertility counselling and tumour banking before starting treatment.

Typical timeline: from first MRI to a full molecular diagnosis in days to a few weeks.

Symptoms

What ATRT can look like in a young child.

Symptoms are often non-specific and can progress quickly. Any combination of these in a young child deserves urgent paediatric assessment.

  • Bulging fontanelle in infants

    A tense, full anterior fontanelle with rapidly increasing head circumference is a classic infant presentation.

  • Vomiting and irritability

    Persistent vomiting (often morning), irritability and poor feeding in a baby or toddler warrant urgent imaging.

  • Developmental regression

    Loss of previously acquired milestones, lethargy or failure to thrive can be the first clue in very young children.

  • Headache and ataxia

    Older children may describe headache, unsteadiness, clumsiness or new problems with balance and coordination.

  • Cranial nerve signs

    Squint, facial weakness, swallowing difficulty or eye-movement problems can reflect brainstem or posterior fossa involvement.

  • Seizures

    New-onset focal or generalised seizures, particularly with supratentorial tumours, need urgent neuroimaging.

  • Hydrocephalus

    Obstruction of cerebrospinal fluid flow raises intracranial pressure and often needs urgent surgical relief.

  • Red flag - rapid deterioration

    Rapid decline over days to weeks in a young child is characteristic. Any concern deserves same-day paediatric assessment.

Treatment

How ATRT is treated in the UK.

Multimodal care in a specialist paediatric neuro-oncology centre: surgery, intensive chemotherapy, proton beam therapy where suitable, trials, and long-term support.

  • Specialist paediatric neuro-oncology MDT

    Care is centralised in UK principal treatment centres such as Great Ormond Street, Alder Hey, Birmingham Children’s, Royal Manchester Children’s, Bristol Royal Hospital for Children, Cambridge Addenbrooke’s and Leeds.

  • Maximum safe surgical resection

    Gross-total resection is the strongest surgical predictor of outcome. Second-look surgery is considered in selected cases after chemotherapy response.

  • High-dose multi-agent chemotherapy

    Regimens combine cyclophosphamide, vincristine, cisplatin, etoposide and methotrexate, often with intrathecal therapy, delivered on EU-RHAB, ACNS0333 or SJYC07-style protocols.

  • High-dose consolidation with stem cell rescue

    Selected protocols use myeloablative chemotherapy with autologous stem cell reinfusion to intensify treatment while sparing radiation in very young children.

  • Proton beam therapy

    Proton beam therapy is preferred for eligible children over 12 to 18 months, focal for localised disease and craniospinal for metastatic. UK PBT is delivered at The Christie in Manchester and UCLH in London.

  • Delayed radiotherapy in infants

    For babies under 12 to 18 months, radiotherapy is delayed or avoided where possible in favour of intensified chemotherapy to protect the developing brain.

  • Targeted therapies and clinical trials

    EZH2 inhibitors (tazemetostat), CDK4/6 inhibitors, aurora kinase inhibitors, immune checkpoint inhibitors and oncolytic viruses are all under study. Trial enrolment is strongly encouraged.

  • Supportive and long-term follow-up

    Hydrocephalus management (ETV or shunt), nutrition, endocrine support, rehabilitation, cognitive follow-up, fertility, psychosocial and family support are integral to care.

What this guide is based on

The sources behind every claim on this page.

International classifications, paediatric neuro-oncology trial protocols and UK service standards, current at the time of last review.

Key references

Guidelines and protocols we relied on.

A quiet reminder

This guide is for information, not medical advice.

Every child with ATRT is different. Your paediatric neuro-oncology team knows your child’s scans, biology and history and is the right source of decisions.

  • WHO Classification of Tumours of the Central Nervous System, 5th edition (2021).

  • EU-RHAB registry and treatment protocol for rhabdoid tumours.

  • Children’s Oncology Group ACNS0333 trial and follow-on protocols for ATRT.

  • St Jude SJYC07 protocol for young children with CNS embryonal tumours.

  • SIOPE (European Society for Paediatric Oncology) rhabdoid tumour guidance.

  • NHS England service specification for paediatric neuroscience and neuro-oncology.

  • Children’s Cancer and Leukaemia Group (CCLG) and The Brain Tumour Charity resources.

Red flags

When to seek urgent help.

Situations that need same-day contact with the treating team, or 999 if life-threatening. Trust your instincts as parents.

  • Rapidly enlarging head in an infant

    A head circumference crossing centiles quickly, with a tense fontanelle, is a paediatric emergency and needs same-day imaging.

  • Reduced consciousness

    Any drowsiness, floppiness or reduced responsiveness in a child with headache or vomiting is a 999 emergency.

  • Acute hydrocephalus

    Sudden worsening headache, vomiting and gaze abnormalities can signal obstruction of cerebrospinal fluid flow requiring urgent neurosurgery.

  • Spinal cord symptoms

    Back pain, leg weakness, new bladder or bowel changes may reflect spinal metastases and need urgent whole-spine MRI.

  • Suspected RTPS in a sibling

    A known family SMARCB1 or SMARCA4 change means siblings and future pregnancies deserve genetic counselling and surveillance.

  • Second rhabdoid tumour

    A new renal or soft-tissue rhabdoid tumour in a child with a brain ATRT strongly suggests germline predisposition.

  • Treatment complications

    Neutropenic fever, severe mucositis, uncontrolled seizures or shunt malfunction all need immediate hospital review.

  • Relapse

    New neurological symptoms after treatment need urgent MRI. Relapsed ATRT carries a very poor prognosis but trials may be available.

  • Late effects

    Endocrine failure, hearing loss, learning difficulties and secondary tumours all warrant structured long-term follow-up.

Living with it

A rare diagnosis, a coordinated village of care.

Four things that make the biggest difference for families walking this path. A specialist team, honest family genetics, protecting the developing brain, and knowing where to find support.

A quiet reminder

You are the constant expert on your child.

The clinical team leads on treatment, but your observations, questions and priorities shape every conversation. Write things down and bring them to every appointment.

  1. 01 Team

    Anchor to a specialist centre

    Care lives in a UK principal treatment centre. Your keyworker, oncologist and clinical nurse specialist are the constants through every phase.

  2. 02 Family

    Genetics is a family matter

    Germline SMARCB1 testing has implications for siblings, parents and future pregnancies. Genetic counselling helps the whole family plan surveillance.

  3. 03 Development

    Protect the developing brain

    Proton beam therapy, careful chemotherapy choices and early rehabilitation all aim to preserve cognition, hearing and endocrine function.

  4. 04 Support

    You are not alone

    Charities such as The Brain Tumour Charity, CCLG, Young Lives vs Cancer and Rhabdoid Tumor Awareness offer practical, emotional and financial support.

Frequently asked

Common questions from families.

Short answers on what ATRT is, molecular subtypes, RTPS, proton beam therapy, treatment and outlook.

  • What is an atypical teratoid/rhabdoid tumour (ATRT)?

    ATRT is a rare, highly aggressive WHO grade 4 embryonal tumour of the central nervous system. It almost always occurs in infants and young children and is defined by loss of the SMARCB1 (INI1) tumour-suppressor gene, or occasionally SMARCA4.

  • How rare is ATRT and who does it affect?

    ATRT accounts for around 1 to 2 per cent of paediatric brain tumours overall, but up to 20 per cent of CNS tumours in infants under 1. The median age at diagnosis is about 2 years and roughly 90 per cent of cases are diagnosed under age 5. Adult cases are very rare.

  • What is rhabdoid tumour predisposition syndrome (RTPS)?

    Around a third of children with ATRT carry a germline SMARCB1 (or rarely SMARCA4) mutation. This is called rhabdoid tumour predisposition syndrome and increases the risk of multiple rhabdoid tumours in the brain, kidney and soft tissues. Families are offered genetic counselling, cascade testing and surveillance.

  • Why is proton beam therapy often preferred?

    Proton beam therapy delivers a highly conformal dose to the tumour and spares nearby developing brain, cochlea, pituitary and other tissues. In young children this can meaningfully reduce cognitive decline, endocrine failure, hearing loss and the risk of secondary tumours compared with conventional photon radiotherapy. UK PBT is delivered at The Christie in Manchester and UCLH in London.

  • What does treatment usually involve?

    Treatment is multimodal: maximum safe surgical resection, high-dose multi-agent chemotherapy (often on EU-RHAB, ACNS0333 or SJYC07-style protocols), sometimes high-dose chemotherapy with autologous stem cell rescue, and radiotherapy (preferentially proton beam) once the child is old enough. Clinical trial enrolment is strongly encouraged.

  • What is the outlook for a child with ATRT?

    Prognosis has historically been very poor but has improved with modern protocols. Overall 5-year survival is now around 25 to 45 per cent, and can reach 60 to 70 per cent for the ATRT-TYR molecular subtype when a gross-total resection is achieved and there is no metastatic disease at diagnosis. Outcomes are guided by age, subtype, extent of resection and response to therapy, and are best discussed with the treating team.

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