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How is Neurofibromatosis Type 1 diagnosed?

How is Neurofibromatosis Type 1 (NF1) diagnosed?

The way the doctor can tell if a person is affected with NF1 is to examine him or her to see if there are signs of the condition, so it’s important to keep an eye out for signs that might help a doctor diagnose NF.

There are specific features that the doctor will look for. NF1 usually appears in childhood and the diagnosis is confirmed if two or more of the following signs are present:

  • Six or more flat, café au lait patches (brown coffee-coloured skin marks), which are the size of a pencil top or bigger. These usually appear during the first year of life and can increase in size and number. Café au lait patches are generally harmless and there is no connection between the number or size of café au lait patches and the severity of the condition. They sometimes fade later in life.
  • Neurofibromas (small benign pea-sized growths or lumps) on or under the skin. These are a common feature of NF1. They usually appear during adolescence and tend to increase in number throughout life.
  • Freckles under the arm or in the groin. Again, these are harmless but can be another sign of NF1.
  • Plexiform neurofibromas. These represent growths around large nerves and can first appear as a swelling.
  • Lisch nodules – these are small pigmented areas in the iris (coloured part of the eye). They are often not visible except during examination with an eye microscope called a slit lamp. Lisch nodules are harmless and never cause symptoms, but can help in making a diagnosis of NF1.
  • Another close family member has NF1.

Why does a person develop NF1?

In around half the people who have NF1, the condition starts up in the individual because a change has happened on one of their genes. This happens before birth and there is no known reason why it occurs. For these individuals, no signs of the condition are found in either of their parents, making it most likely that the gene change (mutation) has occurred for the first time in the affected person. This is known as a ‘spontaneous/new mutation’. The other group of people who have NF1 have inherited the condition from a parent who has NF1.

In either case, at the moment, genetic blood tests are not routinely offered to check if a person has NF1. An experienced doctor diagnoses NF1 by physical examination. Sometimes the features of NF1 take time to appear and therefore it may not be possible to make an immediate diagnosis of NF1. You, or your child, may be asked to come back to see the doctor on another occasion, to be certain of the diagnosis. This can be a frustrating and anxious time for parents, or adults, who are under investigation; however, your doctor will want to be sure that the diagnosis of NF1 is correct.

NF1 does not skip generations. There are two ways in which it occurs: it crops up out of the blue as a first event in an individual, or it is inherited from an affected parent.

Masterclasses in NF: Constitutional Mismatch Repair Deficiency Syndrome as Differential Diagnosis to NF1/Legius Syndrome - Prof. Dr. Katharina Wimmer

Constitutional Mismatch Repair Deficiency Syndrome as Differential Diagnosis to NF1/Legius Syndrome

Prof. Dr. Katharina Wimmer, Medical University of Innsbruck

Masterclasses in NF: Rare NF1-Associated Tumors in Adults - Eric Legius & Prof. Ellen Denayer

Masterclasses in NF: Rare NF1-Associated Tumors in Adults

Eric Legius, MD, PhD, University Hospital Leuven

Prof. Ellen Denayer, University Hospital Leuven

Masterclasses in NF: Optimising Hearing Outcomes in NF2-Related Schwannomatosis - Simon Freeman

Masterclasses in NF: Optimising Hearing Outcomes in NF2-Related Schwannomatosis

Simon Freeman, MPhil FRCS, Manchester Royal Infirmary and Salford Royal Hospital

Masterclasses in NF: NF1 Dermatological Manifestations - Pierre Wolkenstein, Laura Fertitta & Sirkku Peltonen

Masterclasses in NF: NF1 Dermatological Manifestations

Pierre Wolkenstein, MD, PhD, Hopital Henri-Mondor, Paris, France

Laura Fertitta, MD, Hôpital Universitaire Henri Mondor

Sirkku Peltonen, MD, PhD, University of Gothenberg, Sweden

Masterclasses in NF: Breast Cancer in NF1 - Gareth Evans

Masterclasses in NF: Breast Cancer in NF1

Gareth Evans, MD, University of Manchester, UK

Masterclasses in NF: Pain in Non-NF2-Related Schwannomatosis - David Pang

Masterclasses in NF: Pain in Non-NF2-Related Schwannomatosis

David Pang, MD, ChB. Guys and St Thomas' Hospital NHS Trust, London

Masterclasses in NF: Distinguishing Non-NF2-Related from NF2-Related Schwannomatosis - Clinical and Genetic Approaches - Said Farschtschi

Masterclasses in NF: Distinguishing Non-NF2-Related from NF2-Related Schwannomatosis - Clinical and Genetic Approaches

Said Farschtschi, MD, University Medical Center, Hamburg-Eppendorf, Germany

Masterclasses in NF: NF1 Pre-Implantation Genetic Diagnosis - Eric Legius & Prof. Ellen Denayer

Masterclasses in NF: NF1 Pre-Implantation Genetic Diagnosis

Eric Legius, MD, PHD, University Hospital of Leuven, Belgium

Prof. Ellen Denayer, University Hospital of Leuven, Belgium

NF2 Working Together: from a tentative diagnosis and beyond

Understanding the impact that a tentative diagnosis has on a parent. Information and access to the existing NTUK and Specialist Nerve Tumours medical and non medical care network.

NF1 Working Together Part 2: from a tentative diagnosis and beyond

Understanding the impact that a tentative diagnosis has on a parent. Information and access to the existing NTUK and Specialist Nerve Tumours medical and non medical care network.

NF1 Working Together Part 1: from a tentative diagnosis and beyond

Understanding  the impact that a tentative diagnosis has on a parent. Information and access to the existing NTUK and Specialist Nerve Tumours medical and non medical care network.

Masterclasses in NF: Surgery in NF2 - Michel Kalamarides & Andrew King

Masterclasses in NF: Surgery in NF2

Michel Kalamarides, MD, PhD, Hôpital Pitié-Salpêtrière, Paris, France

Prof Andrew King, MBBS FRCS FRCS(SN), Salford Royal Hospital, Manchester, United Kingdom. Member of the MAB of Nerve Tumours UK

Masterclasses in NF: Cognition and Behaviour in NF1: Phenotype and Treatment Approaches - Shruti Garg, Andre Rietman

Masterclasses in NF: Cognition and Behaviour in NF1: Phenotype and Treatment Approaches

Dr Shruti Garg, MBBS, MRCPsych, MMedSci, PhD, Royal Manchester Children’s Hospital, United Kingdom. Member of the MAB of Nerve Tumours UK

Andre Rietman, PhD, Erasmus University Medical Center, Rotterdam, Netherlands

Masterclasses in NF: Emotional Challenges in NF1, NF2 and Schwannomatosis - Susie Henley, Thomas Pletschko & Verena Rosenmayr

Masterclasses in NF: Emotional Challenges in NF1, NF2 and Schwannomatosis

Susie Henley, DClinPsy, PhD, Guy’s and St Thomas’ NHS Foundation Trust, London UK

Thomas Pletschko, PhD, Medical University of Vienna, Austria

Verena Rosenmayr, Clinical Psychologist, Medical University of Vienna, Austria

Masterclasses in NF: NF1 Pediatric Management - Rianne Oostenbrink

Masterclasses in NF: NF1 Pediatric Management

Rianne Oostenbrink, MD, PhD, Erasmus University Medical Center, Rotterdam, Netherlands

Masterclasses in NF: Associated Glioma in Children - the Optic Pathway and Beyond - Amedeo Azizi

Masterclasses in NF: Associated Glioma in Children - the Optic Pathway and Beyond

Amedeo Azizi, MD, PhD, Head of the Paediatric Neurofibromatosis Program and Paediatric Neuro-Oncology Program, Medical University of Vienna, Austria

Masterclasses in NF: NF1 Orthopedic Manifestations - Eric Legius and Christophe Glorion

Masterclasses in NF: NF1 Orthopedic Manifestations

Eric Legius, MD, PhD. Head of Clinical Genetics Department of the University Hospital Leuven, Belgium

Christophe Glorion, MD, PhD, Department of Paediatric Orthopedic and Traumatologic Surgery, Hopital Necker-Enfants Malades, Paris, France. 

Masterclasses in NF: NF1 Malignant Peripheral Nerve Sheath Tumours - Rosalie Ferner and Viktor-Felix Mautner

Masterclasses in NF: NF1 Malignant Peripheral Nerve Sheath Tumours

Prof Rosalie Ferner, Consultant Neurologist and Lead Clinician for Neurofibromatosis, Guy's and St. Thomas' NHS Foundation Trust, London. Member of the MAB of Nerve Tumours UK and Trustee of Nerve Tumours UK

Viktor-Felix Mautner, MD, PhD. University Medical Centre in Hamburg-Eppendorf, Germany. Head of NF Outpatient Department

Masterclasses in NF - Neurofibromatosis Type 1: Cutaneous Neurofibromas - Pierre Wolkenstein and Sirkku Peltonen

Masterclasses in NF - Neurofibromatosis Type 1: Cutaneous Neurofibromas

Pierre Wolkenstein, MD, PhD. Hopital Henri-Mondor, Paris, France. Head of the Department of Dermatology

Sirkku Peltonen MD, PhD. University of Gothenberg, Sweden. Professor of Dermatology

INFER (International NF Educational Resources) is a series of online educational lectures for medical professionals by leading neurofibromatosis experts. The Masterclasses take place online approximately once a month, each on a different topic, and include real-time interaction between the expert presenter and the participants. The presentations are conducted in English, with real-time audio interpretation available in 6 additional languages: French, German, Italian, Portuguese, Russian, and Spanish. A recording of each INFER masterclass is then be made available online in each language for those who could not attend an event. INFER is an initiative of Children’s Tumor Foundation Europe, supported by an educational grant from AstraZeneca. https://ctfeurope.org/research/masterclasses-in-nf

BPNA Keynote Lecture - Prof Rosalie Ferner - Neurofibromatosis 1 in the 21st Century

‘Neurofibromatosis 1 in the 21st Century’

Keynote Lecture at the 48th British Paediatric Neurology Association Annual Scientific Meeting on 21st January 2022

Prof Rosalie Ferner, Consultant Neurologist and Lead Clinician for Neurofibromatosis, Guy's and St. Thomas' NHS Foundation Trust, London. Member of the MAB of Nerve Tumours UK and Trustee of Nerve Tumours UK