Neurofibromatosis Type I

Snapshot

• A 3-year-old female presents with an abnormal “dark spot” in certain parts of the body. The mother reports that these spots began to develop sometime during the last year, but have progressively worsened. The mother also states that her husband has similar skin findings and a history of seizures. On exam, 7-8 uniformly hyperpigmented macules are noted on the chest, back, and buttock. There is freckling in the axilla and inguinal region.

Introduction

• Neurofibromatosis type I (von Recklinghausen disease)
  • most common type of neurofibromatosis
  • autosomal dominant inheritance
    • mutation in NF1 gene on chromosome 17  
      • NF1 gene codes for neurofibromin
        • tumor suppressor that inhibits ras activity via stimulating GTPase
  • variable presentation
• Epidemiology
  • ~50% of cases are inherited
    • the rest are sporadic mutations
• overall risk of malignancy is increased

Presentation

• Physical exam 
  • café-au-lait macules 
  • neurofibromas
    • benign nerve sheath tumor
  • Lisch nodule
    • iris hamartoma
  • optic pathway glioma
  • axillary and inguinal freckling
  • hypertension
• macrocephaly

Evaluation

• Clinical diagnosis
  • e.g., presence of café-au-lait macules, neurofibromas, Lisch nodules, freckling, etc
• Genetic analysis
•  rarely indicated

Differential Diagnosis

• Neurofibromatosis type II
• McCune-Albright syndrome
• MEN 2b
• Familial multiple café-au-lait spots

Treatment

• Dependent on clinical manifestations
  • e.g., surgical intervention for tumor excision
• Annual history and physical for children
• for adults, depends on disease severity

Prognosis, Prevention, and Complications

• Prognosis
  • increased mortality
• Prevention
  • genetic counseling
• Complications
  • increased lifetime cancer risk