Which of the following is the most common tumor

Which of the following is the most common tumor associated with type I neurofibromatosis?


1. Optic nerve glioma.


2. Meningioma.


3. Acoustic Schwannoma.


4. Low grade astrocytoma.


Ans 1


[Ranjita Pallavi, K.J.Somaiya; Mumbai] Neurofibromatosis Type 1 (von Recklinghausen's Disease is am Autosomal dominant disorder. Gene involved = 17, gene product = Neurofibromin.



Criteria for diagnosis of neurofibromatosis type 1 (any two of the following seven will do)
1) Neurofibromas (one plexiform neuroma, or two +)
2)Cafe au lait spots (six or more measuring at least 1.5 cm in greatest dimension)
3)Frekling in axilliary or inguinal areas
4) Two or more iris hamartomas (Lisch nodules)
5) OPTIC GLIOMA
6) Sphenoid dysplasia or thinning of cortex of long bones.
7) Immediate Relative with Neurofibromatosis Type 1
Since, optic nerve glioma is one of the diagnostic criterai for NF 1 it is the commonest. Other tumours associated with NF1 are Astrocytic tumours, neurofibrosarcomas, pheochromocytoma. Compressive myleopathy, compressive peripheral neuropathy and scoliosis also occur.
NF type 2 is also Autosomal dominant, the defect being loacted on chromosome 22. It is characterized by bilateral acoustic neuromas. (remember type 2 -22 chromosome) / (type 1-17 chromosome)