Which one of the following is the most common tumor associated with type I neurofibromatosis - (AIIMS Nov 2013)
|A||Optic nerve glioma|
|D||Low grade astrocytoma|
Optic nerve glioma
Neurofibromatosis type I (Von-Recklinghewsen disease)
o NF-1 is diagnosed when any two of the following seven signs are present.
1. Six or more cafe-au-lait macules
• 5 mm in prepupertal individuals
• 15 mm in postpubertal individuals
• Cafe-au-lait spots are the hallmark of neurofibromatosis and are present in almost 100% of the patient.
2. Axillary or inguinal freckling
3. Two or more Lisch nodules.
• Lisch nodules are hamartomas located within the iris.
4. Two or more neurofibmma or one plexiform neurofibroma.
• Typically involve the skin, but may be situated along peripheral nerves and blood vessels.
• They are small, rubbery lesions with a slight purplish discoloration of the overlying skin.
5. A distinctive osseous lesion.
• Sphenoid dysplasia or cortical thinning of long bones.
6. Optic glioma
7. A first degree relative with NF-l
Other findings are: -
• Pseudoarthrosis of tibia.
• Scoliosis is the most common orthopaedic problem in NF-l, but is no! specific enough to be included as a diagnostic criterian.
• Short stature
• Mental retardation, epilepsy
• Aqueductal stenosis with hydrocephalus
• Meningiomas, ependynomas, Astrocytomas, pheochromocytomas.
NF-1 is caused by mutation in NF-1 gene on chromosome 17 which encodes protein neurofibromin-1.
Neurofibromatosis type -2
o NF-2 may be diagnosed when one of the following two features are present.
1. Bilateral ocoustic neuroma -+ Most distinctive feature
2. A parent, sibling or child with NF-2 and either unilateral eighth nerve masses or any two of the following -)
o Neurofibroma, meningioma, glioma, Schwannoma or juvenile post subcapsular cataract.
• NF-2 is cause by mutation in NF-2 gene on chromosome 22 that encodes for protein neurofibromin 2, Schwannomin or merlin.