Phys · dermatological
Genodermatoses with Systemic Significance
Also known as Genodermatoses with Systemic Significance · genodermatoses with systemic significance · neurofibromatosis type 1 · tuberous sclerosis complex · Sturge-Weber syndrome · hereditary haemorrhagic telangiectasia · pseudoxanthoma elasticum · Darier disease · X-linked ichthyosis
Consultant-physician depth guide to genodermatoses with systemic significance for FRACP DWE/DCE — neurofibromatosis type 1 (NF1) revised diagnostic criteria and MEK inhibitor therapy for plexiform neurofibromas, tuberous sclerosis complex (TSC) with mTOR inhibitors, Sturge-Weber syndrome and GNAQ mosaicism, hereditary haemorrhagic telangiectasia (Curaçao criteria), X-linked ichthyosis with STS deficiency, Darier disease (ATP2A2), pseudoxanthoma elasticum (ABCC6), and the multisystem surveillance the physician must orchestrate. Structured for FRACP DWE/DCE, MRCP and ABIM preparation.
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Target exams
Red flags
- Six or more café-au-lait macules in a prepubertal child, axillary freckling, two or more neurofibromas and a first-degree relative meet revised NF1 diagnostic criteria — orchestrate ophthalmology, MRI and blood pressure screening rather than waiting for the full phenotype
- Hypomelanotic ash-leaf macules in an infant plus seizures demands urgent evaluation for tuberous sclerosis complex — early electroencephalogram, brain MRI and echocardiogram for rhabdomyoma
- A facial port-wine stain in the V1 trigeminal distribution coexisting with seizures or hemiparesis is Sturge-Weber syndrome — early aspirin and anticonvulsant therapy modify the high risk of stroke-like episodes
- Recurrent epistaxis with mucocutaneous telangiectases and a first-degree relative meets Curaçao criteria for hereditary haemorrhagic telangiectasia — screen for pulmonary, hepatic and cerebral arteriovenous malformations before they declare with haemorrhage
- Plucked-chicken neck skin, angina at a young age and retinal angioid streaks signal pseudoxanthoma elasticum — arterial disease and gastrointestinal bleeding may precede the dermatology presentation
Genodermatoses with Systemic Significance — Skin as the Window to the Genome
The answer first
Genodermatoses are inherited skin disorders in which a visible cutaneous sign is the clue to a multisystem disease. The physician's job is to recognise the pattern, apply the consensus diagnostic criteria, and then orchestrate the surveillance — ophthalmology, cardiology, neurology, gastroenterology, oncology — that these syndromes demand. [1]
A consultant-grade answer rests on four pillars: [1]
- Apply the published diagnostic criteria before accepting the label. NF1 uses the revised Legius 2021 consensus, TSC uses the 2021 International criteria, HHT uses the Curaçao criteria, and Sturge-Weber is clinical plus the somatic GNAQ mosaic finding — each set of criteria defines who needs molecular testing and who needs imaging. [1] [2] [3] [4]
- Surveil the dangerous systemic complications in advance, not after they declare. NF1 mandates annual blood pressure and ophthalmology through childhood plus MRI for plexiform neurofibromas; TSC mandates brain MRI, renal ultrasound and echocardiography; HHT mandates pulmonary and cerebral AVM screening; pseudoxanthoma elasticum mandates retinal and cardiovascular surveillance. [9] [10] [6]
- Recognise the new disease-modifying therapies that have changed outcomes. Selumetinib (an oral MEK1/2 inhibitor) is now licensed for symptomatic, inoperable plexiform neurofibromas in NF1, and everolimus (mTOR inhibitor) for subependymal giant-cell astrocytoma and renal angiomyolipoma in TSC. [8] [2]
- Counsel families with accurate inheritance risk. NF1, TSC, HHT and PXE are autosomal dominant with variable expressivity; Sturge-Weber and most Darier disease are sporadic or somatic; X-linked ichthyosis is X-linked recessive and carrier mothers of affected sons carry a contiguous gene deletion risk in subsequent pregnancies. [1] [7]
DWE high-yield: "The skin is the map." Six café-au-lait macules plus axillary freckling is NF1; ash-leaf hypomelanosis plus seizures is TSC; a V1 port-wine stain plus hemiparesis is Sturge-Weber; recurrent epistaxis with mucocutaneous telangiectases is HHT — each cutaneous pattern unlocks a defined surveillance programme that the physician must initiate. [1] [2] [3] [4]
References12ShowHide
- [1]Legius E, Messiaen L, Wolkenstein P, et al. Revised diagnostic criteria for neurofibromatosis type 1 and Legius syndrome: an international consensus recommendation. Genet Med, 2021.PMID 34012067
- [2]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
- [3]McDonald J, Bayrak-Toydemir P, DeMille D, et al. Curaçao diagnostic criteria for hereditary hemorrhagic telangiectasia is highly predictive of a pathogenic variant in ENG or ACVRL1 (HHT1 and HHT2). Genet Med, 2020.PMID 32300199
- [4]Ramirez EL, Jülich K Sturge-Weber syndrome: an overview of history, genetics, clinical manifestations, and management. Semin Pediatr Neurol, 2024.PMID 39389653
- [5]Ettinger M, Kimeswenger S, Deli I, et al. Darier disease: Current insights and challenges in pathogenesis and management. J Eur Acad Dermatol Venereol, 2025.PMID 39606894
- [6]Germain DP Pseudoxanthoma elasticum. Orphanet J Rare Dis, 2017.PMID 28486967
- [7]Zhou B, Liang C, Li P, et al. Revisiting X-linked congenital ichthyosis. Int J Dermatol, 2025.PMID 39086014
- [8]Chen AP, Coyne GO, Wolters PL, et al. Efficacy and safety of selumetinib in adults with neurofibromatosis type 1 and symptomatic, inoperable plexiform neurofibromas (KOMET): a multicentre, international, randomised, placebo-controlled, parallel, double-blind, phase 3 study. Lancet, 2025.PMID 40473450
- [9]Kerashvili N, Gutmann DH The management of neurofibromatosis type 1 (NF1) in children and adolescents. Expert Rev Neurother, 2024.PMID 38406862
- [10]Hammill AM, Wusik K, Kasthuri RS Hereditary hemorrhagic telangiectasia (HHT): a practical guide to management. Hematology Am Soc Hematol Educ Program, 2021.PMID 34889398
- [11]Miller DT, Freedenberg D, Schorry E, et al. Health Supervision for Children With Neurofibromatosis Type 1. Pediatrics, 2019.PMID 31010905
- [12]Wataya-Kaneda M Tuberous Sclerosis Complex. Keio J Med, 2025.PMID 37532517