"The same syndromic features has also been reported to occur due to non-mass lesions or mass lesions that do not directly compress an optic nerve, and these cases are referred to as pseudo-Foster Kennedy syndrome 3-8. Indeed, these are considered to be more common as the aetiology for this constellation of clinical features 8. Some causes include 3-8:"
"Furthermore, the description pseudo-pseudo-Foster Kennedy syndrome has been employed in one case report 8. This report describes a case of Foster Kennedy syndrome alongside concurrent contralateral non-arteritic anterior ischaemic optic neuropathy such that one nerve was atrophied due to the direct compression from a meningioma and the other nerve was swollen due to both raised intracranial pressure and the non-arteritic anterior ischaemic optic neuropathy 8. This is likely to be a very rare coincidental entity."
"Foster Kennedy syndrome, by definition, is caused by a compressive mass 1,2. This mass directly compresses one optic nerve, accounting for ipsilateral optic nerve atrophy, and causes chronic raised intracranial pressure resulting in contralateral papilloedema 1,2. Thus, in order to cause such a constellation of symptoms, masses are usually located in the olfactory groove, falx cerebri, sphenoid wing, or subfrontal region 1,2. The most commonly reported mass is a meningioma, although a number of other causes have been reported such as craniopharyngiomas, pituitary adenomas, neuroblastomas, and rarely aneurysms and frontal lobe abscesses 1,2."