Bare right orbit - sphenoid dysplasia due to neurofibromatosis (type 1)
Known NF1. Right proptosis ? mass in optic nerve. Normal acuity.
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Well-defined defect in the right sphenoid allowing the inferior right frontal lobe to herniate into the right orbit extrinisically compressing the right optic nerve - can cause a pulsatile exophthalmos. Note absence of the lesser wing of sphoid line in the right orbit as compared with the left (arrows). This is responsible for the "bare" orbit.
This is a bone dysplasia allowing the frontal lobe to herniate not a bone erosion due to en plague meningioma, neurofibroma or other tumour. Note in this case the innominate line (tangential greater wing of sphenoid) remains intact rather it is the lesser wind of spenoid (arrow on the left) that is eroded letting the frontal rather than the more typical temporal lobe to herniate.