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Page 2 of 15 Okafor et al. Mini-invasive Surg 2024;8:28 https://dx.doi.org/10.20517/2574-1225.2023.128

[1]
olfactory neuroepithelium . It accounts for 2% to 6% of nasal cavity and paranasal sinus cancer cases with
[2-5]
an incidence rate of 0.4 per million population . Most cases occur in individuals aged between 35 and 70
[6]
years with a mean age of presentation of 53 years . There is a moderate male predominance with a male-to-
[6]
female ratio of 59 to 41 .
Diagnosing olfactory neuroblastoma involves a nasal cavity examination and a tissue biopsy. While there is
[7,8]
no universally employed staging system, the Kadish and Dulguerov systems are commonly used . Imaging
modalities such as computed tomography (CT), magnetic resonance imaging (MRI) and positron emission
tomography (PET) scan are particularly valuable for assessing regional and distant metastases, and staging.

The behavior of olfactory neuroblastoma varies widely, ranging from less aggressive, slowly growing tumors
with extended survival to highly aggressive malignancies, characterized by rapid recurrence and spread of
cancer to distant sites . This diversity in tumor severity, coupled with its rarity and the limited data
[9]
regarding genetic and molecular alterations, leads to some uncertainties surrounding the best practices for
management . Currently, treatment involves surgery, radiation therapy, and/or chemotherapy followed by
[10]
long-term surveillance to monitor treatment outcomes and recurrences .
[11]
Ultimately, this chapter explores the clinical characteristics, diagnostic modalities, staging, treatment
options, outcomes, and recent advances in our understanding of this disease.

CLINICAL PRESENTATION
Olfactory neuroblastoma typically manifests with a variety of nonspecific symptoms, with nasal obstruction
manifesting as the most prevalent symptom. This is primarily attributed to the space-occupying effect of the
nasal cavity mass. Obstruction or local invasion of adjacent structures explains other common symptoms,
including the paranasal sinuses (headache, facial swelling), the nasolacrimal duct (epiphora), cribriform
plate (anosmia), eustachian tube (middle ear effusion, otalgia, recurrent acute otitis media), and orbit
(diplopia, proptosis, other visual changes) [12-14] . Alongside nasal obstruction, patients may experience other
symptoms, including nasal discharge, epistaxis, and/or varying degrees of pain . Due to the anatomic
[15]
etiology of these symptoms, patients will report ineffective trials of medical therapy prior to referral to the
appropriate specialist. Rigid nasal endoscopy commonly reveals a unilateral, polypoid, glistening firm pink-
gray mass with irregular and friable mucosa. Given its sensory neuroepithelial olfactory cell origin, the mass
often occupies areas in which these cells reside: the superior portion of the nasal septum and olfactory cleft,
superior nasal concha, roof of the nose, and cribriform plate of the ethmoid sinus . Rarely, olfactory
[16]
neuroblastoma has been noted to originate in the nasopharynx or sphenoid sinus [16-18] . Hypervascularization
of the tumor is common, consistent with the common complaint of epistaxis.

While relatively rare, olfactory neuroblastoma can give rise to paraneoplastic syndromes secondary to excess
hormone production. Such syndromes include ectopic adrenocorticotropic hormone (ACTH)
syndrome [19,20] , hypercalcemia , hyponatremia , syndrome of inappropriate antidiuretic hormone
[19]
[21]
[22]
[23]
(SIADH) , and various neurological paraneoplastic syndromes . Rare reports of atypical presentations
such as oral paresthesia and tooth laxity as the only presenting symptoms further add to the clinical
heterogeneity of olfactory neuroblastoma . Ultimately, these nonspecific symptoms may result in
[24]
misdiagnosis, delaying definitive diagnosis and appropriate management . Thus, it is imperative to execute
[4]
a thorough diagnostic workup.