62. Neurofibromatosis
Definition
Neurofibromatosis is a familial, multisystem, genetic disorder characterized by developmental changes in the nervous system, muscles, bones, and skin. It is marked by the formation of neurofibromas over the entire body and associated with areas of pigmentation. Neurofibromatosis is also known as von Recklinghausen’s disease.
Incidence
The estimated frequency of neurofibromatosis is 1:3000 to 1:4000 people. The actual incidence may be higher.
Etiology
The cause of neurofibromatosis is mutation or deletion of the NF1 gene, which is found on the long arm of chromosome 17, resulting in decreased production of neurofibromin. The precise role of neurofibromin is still not fully understood, but this gene product has a multitude of effects and diverse functions in several tissues.
Diagnostic Criteria for Neurofibromatosis
Diagnosis requires the presence of two or more of the following seven criteria:
1. Six or more café-au-lait spots or hyperpigmented macules (5 mm in diameter for children younger than 10 years of age or 15 mm in adults)
2. Axillary or inguinal freckles
3. Two or more neurofibromas or one plexiform neurofibroma
4. Two or more iris hamartomas (Lisch nodules)
5. Sphenoid dysplasia or long-bone abnormalities (e.g., pseudoarthrosis)
6. First-degree relative with neurofibromatosis
7. Optic nerve glioma
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| Neurofibromatosis. Neurofibromas. |
Signs and Symptoms
• Axillary or inguinal freckles
• Café-au-lait spots
• Congenital pseudoarthrosis
• Forearm bowing
• Hypertension
• Macrocephaly
• Noncorrectable vision loss
• Optic nerve tumors
• Plexiform neurofibromas with or without hypertrichosis or hyperpigmentation
• Pruritus
• Scoliosis with or without kyphosis
• Sphenoid bone dysplasia
• Subcutaneous or cutaneous neurofibromas
• Thinning and angulation of long bones
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