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Page 6 of 13 Tang et al. Mini-invasive Surg 2024;8:24 https://dx.doi.org/10.20517/2574-1225.2024.04

resection. SNMT pathologies with available literature selected for further discussion regarding the utility of
EES include ONB, adenocarcinomas, ACC, SCC, SNUC, and SNMM. Findings are summarized in Table 1.

Olfactory neuroblastoma
Surgical resection with negative margins and adjuvant radiation therapy is the gold standard for most cases.
However, IC may be considered for locally advanced or recurrent disease [38-41] . In these cases, patients with
[42]
good response to IC may be treated with chemoradiation therapy . In addition, pediatric ONB is often
extensive and invasive and responds well to IC, making this the typical treatment pathway in children .
[43]
EES plays an accepted role in the resection of this tumor, showing encouraging outcomes. In a meta-
analysis by Devaiah et al. comparing endoscopic with open surgery, endoscopic surgery was associated with
better 10-year survival (90% vs. 65%) . A retrospective review of 139 patients diagnosed with ONB at MD
[44]
Anderson Cancer Center was performed between 1991 and 2016, with 72 (69.4%) patients having been
[28]
treated with EES . Endoscopic approaches, either pure endoscopic or endoscopic assisted, were found to
be suitable for surgical resection of appropriately selected patients with ONB. In addition, Gallia et al.
reported on an 11-year experience of 20 patients with ONB treated with purely endonasal endoscopic
techniques and found 5-year overall, disease-specific, and recurrence-free survival rates were 92.9%, 100%,
and 92.9%, respectively . In cases where patients have extensive skull base involvement including dural
[29]
invasion or orbital invasion, an endoscopic approach can be combined with open approaches if necessary to
achieve gross total resection . This is purely determined by anatomy and not simply the presence of
[45]
invasion. Invasion of dura or periorbita lateral to the mid orbit may require an open approach; however,
dural and intracranial involvement is not an absolute limitation for EES . Rarely, the frontal sinus cannot
[46]
be fully cleared and requires a bicoronal incision and frontal sinus cranialization.

ONB case presentation
A 68-year-old woman presented with nasal congestion, anosmia, and intermittent headaches. Magnetic
resonance imaging (MRI) showed a sinonasal mass with bony invasion of medial orbit and fovea
ethmoidalis invasion, and bilateral dural and olfactory bulb involvement [Figure 2]. A gross total resection
with negative margins was performed using EES with bilateral resection of dura and olfactory tracts.

Adenocarcinoma
Adenocarcinomas typically arise within the ethmoid sinuses. Resection remains the primary treatment
modality and endoscopic surgical excision has been shown to have comparable oncological results to open
approaches while providing less morbidity [47,48] . In a multicenter study of 159 patients, Vergez et al. found
that EES and transfacial approaches had comparable early oncological outcome and morbidity, but
hospitalization was significantly reduced in patients treated with EES . In a meta-analysis of 39 articles
[49]
pooling 1,826 patients, EES was associated with lower rates of major and minor complications (16.6%) when
compared to open approaches (43.8% . Of note, postoperative RT was utilized in the majority of cases in
)[47]
this metanalysis. In a dual-institutional case-control study, EES was shown to be an effective single
treatment modality for primary early-stage low-grade adenocarcinoma resected with negative margins . In
[50]
adenocarcinomas, comparative studies have found EES to be as effective as open approaches although select
patients with extensive invasion of the skull base beyond the anatomic limits of endonasal resection (mid
orbit, frontal sinus) may benefit from a combined approach.

SCC
In 2010, the European position paper on endoscopic management of tumors of the nose, paranasal sinuses,
and skull base found that only 23 patients underwent purely EES among 150 patients with sinonasal SCC .
[51]
This is possibly related to the aggressive nature of SCC, which has a tendency to have both local invasion
and perineural invasion, but also may reflect the lack of widespread acceptance of EES to the skull base at