Granular cell tumor of the optic nerve.

A case of a combined neurofibroma-granular cell tumor is presented. The tumor had developed in the left middle cranial fossa after an intracranial trigeminal nerve operation 23 years before. It had displaced and infiltrated the temporal lobe and expanded probably via the fissura orbitalis into the orbit. The thickened optic nerve revealed a marked widening of the subdural fissure by typical granular cells. The cufflike tumor cell aggregation in the subdural fissure had compressed the optic fascicle, thereby inducing a demyelinisation and axonal degeneration. A reactive gliosis in the optic fascicle masks the typical pattern of the optic nerve atrophy. The gangliocytes of the third retinal neuron are atrophic and replaced by reactively proliferated fibrillary astrocytes. A short review of the literature and theories concerning histogenesis of the granular cell tumor (neurogenic or mesoderma) is given. An intermediary type of neurofibromatous and granular cells which we found motivates us to agree with a mesodermal origin.