Comments on "Schwannomas from Olfactory Nerve: A Rare Type".

Abstract

I must thank the authors for critically following our article entitled “A large extra cranial cystic trigeminal schwannoma of the parapharyngeal space – exploring the right approach” published in the Indian Journal of Surgical Oncology [1]. The authors have pointed out that schwannomas account for nearly 8 % of all intracranial tumors and can arise from any nerve containing Schwann cells. They further they go on to state that the olfactory nerve is NOT prone to schwannomas due to the lack of a Schwann cell layer. In effect we also have reported the same in our introductory statement which states that “Schwannomas can originate from any peripheral, cranial or autonomic nerve of the body with the exception of the olfactory nerve and the optic nerve.” This statement has been substantiated by many authors including the most comprehensive systematic review on olfactory groove schwannomas by Figueiredo et al. [2]. It is vitally important to appreciate the fact that that the term “olfactory schwannomas” SHOULD NOT be considered synonymous with schwannomas arising from the olfactory nerve. The term “olfactory schwannoma” has in fact been used to describe anterior cranial fossa schwannomas unrelated to the cranial nerves. “Subfrontal schwannomas” and “olfactory groove schwannomas” are the other terminologies that have been used to describe this condition. The different terminologies, the rarity and the enigmatic origin further complicate our understanding of these intracranial schwannomas. Figueiredo et al. [2] have clearly demonstrated that the origin these rare schwannomas are NOT from the olfactory tract, a fact substantiated by other authors as well [3, 4] Further in an attempt to standardize the terminologies, they suggest avoiding the usage of the terms “subfrontal schwannomas” or “olfactory schwannomas” and have suggested the use of the term “olfactory groove schwannoma” which better describes its origin and pathogenesis of this rare tumor [2].