Paeds · paediatric-dermatology
Genodermatoses and neurocutaneous skin findings
Also known as Neurofibromatosis type 1 · NF1 · Tuberous sclerosis complex · TSC · Sturge-Weber syndrome · Phakomatosis · Neurocutaneous syndrome · Café-au-lait macule · Angiofibroma · Port-wine stain
Fellowship topic on paediatric genodermatoses and neurocutaneous skin findings: the three classic phakomatoses — neurofibromatosis type 1 with its café-au-lait macules, skinfold freckling, neurofibromas and the NIH diagnostic criteria; tuberous sclerosis complex with its hypomelanotic ash-leaf macules, facial angiofibromas, shagreen patch and the major-minor diagnostic criteria; and Sturge-Weber syndrome with its forehead port-wine stain, leptomeningeal angioma and glaucoma. The shared biology is the RAS-MAPK and mTOR signalling pathways — NF1 loss unleashes RAS-MAPK through absent neurofibromin, TSC1 or TSC2 loss drives mTOR overactivation, and a somatic mosaic GNAQ mutation fixes the Sturge-Weber port-wine stain. Management turns on recognising that the skin lesion is the entry point to brain and systemic disease: optic pathway glioma and malignant peripheral nerve sheath tumour surveillance in NF1, vigabatrin for infantile spasms and everolimus for subependymal giant cell astrocytoma in TSC, and seizure, glaucoma and stroke-like-episode care in Sturge-Weber — with ANZ, UK, US and Canada guidance.
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Target exams
Red flags
- Six or more café-au-lait macules or axillary and inguinal freckling in a child — assess for neurofibromatosis type 1 against the NIH criteria and arrange optic pathway and blood pressure surveillance
- A child with tuberous sclerosis and new or worsening seizures, especially epileptic spasms — electroencephalography, first-line vigabatrin, and image for subependymal giant cell astrocytoma
- A port-wine stain on the forehead or upper eyelid in an infant — screen for Sturge-Weber syndrome with neurological assessment, contrast brain MRI and ophthalmology for glaucoma
- A rapidly growing, painful, firm or new neurological deficit in a known neurofibromatosis type 1 lesion — possible malignant peripheral nerve sheath tumour; refer urgently for imaging and biopsy
- An infant with tuberous sclerosis and a growing lesion near the foramen of Monro with ventriculomegaly — subependymal giant cell astrocytoma with obstructive hydrocephalus; urgent neurosurgery and mTOR inhibitor assessment
Life stages
Care settings
Clinical exam formats
Board mappings
- General Paediatrics and Dermatology: recognition of the phakomatoses — café-au-lait macules and freckling of NF1, ash-leaf macules and angiofibromas of TSC, and the port-wine stain of Sturge-Weber
- Neurology and genetics: the NIH diagnostic criteria for NF1 and the major and minor criteria for TSC
- Renewed curriculum — Genetics and multisystem disease: the RAS-MAPK and mTOR pathway biology that links neurofibromin, hamartin-tuberin and GNAQ
- Complex care: multidisciplinary surveillance and the role of mTOR inhibition and MEK inhibition
- General Paediatrics: recognition of neurocutaneous skin signs and the red flags that mandate neurological and ophthalmological referral
- Neonatology and dermatology: the port-wine stain on the forehead and the ash-leaf macule in the newborn
- Long Case / Structured discussion: a child with neurofibromatosis type 1 — criteria, optic pathway glioma surveillance, learning and blood pressure, and malignant peripheral nerve sheath tumour risk
- Communication station: explaining a neurocutaneous syndrome diagnosis, inheritance and surveillance to a family
- Level 2 / 3 — Dermatology and Neurology: the phakomatoses and their multisystem complications
- Neurodisability: developmental and learning surveillance in NF1 and TSC
- Foundation of Practice (FOP): café-au-lait macules, ash-leaf macules and the facial port-wine stain
- Applied Knowledge in Practice (AKP): the diagnostic criteria, inheritance and complications of the three phakomatoses
- History-taking and management: an infant with a forehead port-wine stain and the Sturge-Weber screen
- Communication: explaining inheritance, surveillance and safety-netting to a family
- General Pediatrics Content Outline — neurocutaneous syndromes: recognition, diagnostic criteria and referral
- Neurology and Genetics: NF1, TSC and Sturge-Weber and their complications
- Patient Care: recognition, risk-stratification and stepwise surveillance of the neurocutaneous syndromes
- Medical Knowledge: the NIH criteria, the major-minor criteria, RAS-MAPK and mTOR biology, and the role of mTOR and MEK inhibition
- Systems-Based Practice: multidisciplinary referral for the multisystem complications of the phakomatoses
- Medical Expert: diagnosis and surveillance of NF1, TSC and Sturge-Weber syndrome
- Collaborator and Health Advocate: coordination of multidisciplinary care and equitable access to specialist services
- Communicator: explaining inheritance, surveillance and safety-netting to families
Inherited versus mosaic — two routes to a neurocutaneous syndrome
Inherited (NF1, TSC)
Sporadic mosaic (Sturge-Weber)
The phakomatoses share a signalling story. Neurofibromatosis type 1 loses the NF1 gene product neurofibromin, so RAS stays switched on and the RAS-MAPK cascade overfires, growing melanocytes and nerve-sheath cells. Tuberous sclerosis loses the hamartin-tuberin brake, so mTOR runs unchecked and grows dysplastic hamartomatous tissue. Sturge-Weber is the odd one out — a mosaic GNAQ mutation fixes malformed vessels in one territory. Remember: lose a brake on a growth pathway, and the skin, brain and eye all feel it. [4] [5]
Overview & Definition
Picture a four-year-old brought in because the teacher has noticed brown patches on the skin and some difficulty with reading, or a newborn with a dark-red stain covering half the forehead, or an infant suddenly flexing in clusters with a faint white leaf-shape on the back. Each is the everyday face of a neurocutaneous syndrome, and each demands that the clinician see the skin sign as a window onto the brain. [3] [11]
Genodermatoses are inherited skin disorders, and the neurocutaneous syndromes — historically called phakomatoses — are those in which the skin lesion travels with disease of the brain, eye and other organs. The three that dominate paediatric practice are neurofibromatosis type 1, tuberous sclerosis complex and Sturge-Weber syndrome. They are united less by a single lesion than by a lesson: the visible cutaneous marker is often the earliest and most reliable clue to hidden neurological, ophthalmological and systemic disease. [1] [4]
The clinician's task has three layers. The first is to recognise the skin sign and name the syndrome against a set of diagnostic criteria, because the criteria drive the surveillance that follows. The second is to find the hidden complications early — the optic pathway glioma, the epilepsy, glaucoma, cardiac or renal tumour, the malignant transformation — before they damage the developing brain. The third is to coordinate the multidisciplinary care that these multisystem diseases demand, because no single organ defines the outcome. [1] [5]
References12ShowHide
- [1]Gutmann DH; Aylsworth A; Carey JC; et al The diagnostic evaluation and multidisciplinary management of neurofibromatosis 1 and neurofibromatosis 2. JAMA, 1997.PMID 9207339
- [2]National Institutes of Health Consensus Development Panel Neurofibromatosis. Conference statement. National Institutes of Health Consensus Development Conference. Arch Neurol, 1988.PMID 3128965
- [3]Williams VC; Lucas J; Babcock MA; et al Neurofibromatosis type 1 revisited. Pediatrics, 2009.PMID 19117870
- [4]Gutmann DH; Ferner RE; Listernick RH; et al Neurofibromatosis type 1. Nat Rev Dis Primers, 2017.PMID 28230061
- [5]Northrup H; Aronow ME; Bebin EM; et al Updated International Tuberous Sclerosis Complex Diagnostic Criteria and Surveillance and Management Recommendations. Pediatr Neurol, 2021.PMID 34399110
- [6]Northrup H; Krueger DA; International Tuberous Sclerosis Complex Consensus Group Tuberous sclerosis complex diagnostic criteria update: recommendations of the 2012 International Tuberous Sclerosis Complex Consensus Conference. Pediatr Neurol, 2013.PMID 24053982
- [7]Krueger DA; Northrup H; International Tuberous Sclerosis Complex Consensus Group Tuberous sclerosis complex surveillance and management: recommendations of the 2012 International Tuberous Sclerosis Complex Consensus Conference. Pediatr Neurol, 2013.PMID 24053983
- [8]Franz DN; Belousova E; Sparagana S; et al Efficacy and safety of everolimus for subependymal giant cell astrocytomas associated with tuberous sclerosis complex (EXIST-1): a multicentre, randomised, placebo-controlled phase 3 trial. Lancet, 2013.PMID 23158522
- [9]Shirley MD; Tang H; Gallione CJ; et al Sturge-Weber syndrome and port-wine stains caused by somatic mutation in GNAQ. N Engl J Med, 2013.PMID 23656586
- [10]Lo W; Marchuk DA; Ball KL; et al Updates and future horizons on the understanding, diagnosis, and treatment of Sturge-Weber syndrome brain involvement. Dev Med Child Neurol, 2012.PMID 22191476
- [11]Comi AM Update on Sturge-Weber syndrome: diagnosis, treatment, quantitative measures, and controversies. Lymphat Res Biol, 2007.PMID 18370916
- [12]Yeom S; Comi AM Updates on Sturge-Weber Syndrome. Stroke, 2022.PMID 36263782