Optic chiasm neurofibroma

Neurofibromatosis type I (NF-1) is a complex multi-system human disorder caused by the mutation of a gene on chromosome 17 that is responsible for production of a protein, called neurofibromin, which is needed for normal function in many human cell types. NF-1 causes tumors along the nervous system which can grow anywhere on the body. [Source: Wikipedia ]

May Cause
Omega sella