Updated: 8/10/2020

Neurofibromatosis Type I

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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
 

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Questions (4)
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(M1.NE.15.17) A 14-year-old boy presents as a new patient to your practice. While conducting your physical exam, you observe the findings depicted in Figures A and B. Which of the following additional findings would most likely be found in this patient? Tested Concept

QID: 105017
FIGURES:
1

The presence of ash-leaf spots

15%

(22/149)

2

Astrocytomas

12%

(18/149)

3

Facial angiofibromas

17%

(25/149)

4

Iris hamartomas

50%

(75/149)

5

A white tuft of scalp hair since birth

4%

(6/149)

M 2 E

Select Answer to see Preferred Response

(M1.NE.15.0) A 50-year-old male presents to the dermatologist for a large, soft, cutaneous nerve sheath tumor on his right eyelid resulting in a vision deficit. On physical exam, hyperpigmented macules and numerous other tumors can be seen across his body along with freckling in the inguinal and axillary areas (Figure A & B). His past medical history is significant for loss of vision in his left eye due to an optic glioma at the age of 20. His family history is notable for several members on his mother's side (grandmother, mother, uncle, and brother) having a similar presentation. Genome analysis reveals that the gene is located on chromosome 17. Which of the following genes is most likely mutated? Tested Concept

QID: 107027
FIGURES:
1

VHL

5%

(4/82)

2

RB

0%

(0/82)

3

NF-1

94%

(77/82)

4

WT-1

1%

(1/82)

5

BRCA-1

0%

(0/82)

M 2 E

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(M1.NE.14.72) A 27-year-old Caucasian man presents for a routine visit to his primary care physician. He does not have any complaints at this time. On physical exam he is noted to have numerous firm, rubbery nodules of varying sizes on his back (see Figure A). He also has small darkly pigmented spots on his irises as well as a hyperpigmented, macular skin lesion measuring 3x5 cm on his right medial thigh. Which of the following is a complication of this patient's genetic condition? Tested Concept

QID: 106525
FIGURES:
1

Bilateral acoustic schwannomas

23%

(19/82)

2

Cardiac rhabdomyomas

6%

(5/82)

3

Optic gliomas

60%

(49/82)

4

Retinal hemangioblastomas

7%

(6/82)

5

Renal angiomyolipomas

4%

(3/82)

M 2 D

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