Sphenoid esthesioneuroblastoma arising from the hindmost olfactory filament
Introduction
Esthesioneuroblastoma (ENB), or olfactory neuroblastoma, is a rare malignant neoplasm arising from the olfactory neuroepithelium. It is an uncommon tumor accounting for less than 5% of all malignant nasal tumors [1]. Typically, ENBs are found in the olfactory cleft with extension to the ethmoid sinuses or anterior skull base. ENBs located outside this region, where the olfactory neuroepithelium does not normally exist, have been reported as ectopic ENBs [2], [3], [4], [5].
Here, we report a case of ENB arising from the sphenoid sinus. During endoscopic transnasal surgery, a connection between the tumor and the hindmost olfactory filament was confirmed, suggesting that the tumor was not ectopic, but arose from the normal olfactory neuroepithelium. This article was approved by the ethical committee of Graduate School of Medicine, Kyoto University (#1102).
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Case report
A 46-year-old male patient presented with epistaxis from the right nasal cavity and underwent a check-up at a general hospital. Examinations revealed a reddish mass filling the right sphenoethmoidal recess. Histology from biopsies showed ENB. The patient was referred to our hospital for surgical treatment.
Preoperative computed tomography (CT) showed that a soft tissue density area occupied the right sphenoid sinus with extension to the nasal cavity (Fig. 1A, B). Gadolinium-enhanced T1-weighted
Discussion
Development of ENB outside the region in which the olfactory epithelium is present has been termed as ectopic ENB. A review of the literature revealed 16 previously described cases of ectopic ENB [2], [3], [4], [5]. Several sources of ectopic ENBs have been proposed, including rests of the vomeronasal organ, persistent terminal ganglion cells, and autonomic ganglion cells in the sinuses. Regarding the anatomical location, 9 of the 16 ectopic ENBs in literatures [2], [3], [4], [5] originated in
Competing interest
All authors declare that they have no competing interests.
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