Which one of the following is the most common tumor associated with type I neurofibromatosis –
Optic nerve glioma
Meningioma
Acoustic schwannoma
Low grade astrocytoma
Neurofthromatosis type (Von-Reeltdinghewsen disease) 

NF-1 is diagnosed when any two of the following seven signs are present.

1. Six or more cafe-au-gait 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 frecking
3. Two or more Lisch nodules.

Lisch nodules are hamartomas located within the iris.

4. Two or more neurofibroma 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-1
Other findings are : -

Pseudoarthrosis of tibia.
Scoliosis is the most common orthopaedic problem in NF-1, but is not specific enough to be included as a diagnostic criterian.
Short stature


Mental retardation, epilepsy


Hypertension


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 

NF-2 may be diagnosed when one of the following two features are present.


Bilateral ocoustic neuroma --> Most distinctive feature
A parent, sibling or child with NF-2 and either unilateral eighth nerve masses or any two of the following 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.