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Sell et al. Mini-invasive Surg 2024;8:3 https://dx.doi.org/10.20517/2574-1225.2023.105 Page 3 of 10

[14]
endoscopic examination more difficult but can also complicate identifying recurrence by exam . Khalili
et al. found that while endoscopy has a lower sensitivity for the detection of recurrences compared to
[15]
imaging (25% vs. 75%), they had similar specificity (89% vs. 90%) . Kahlili et al. also demonstrated that the
positive predictive value (PPV) of endoscopy is significantly higher when used to evaluate recurrence in
symptomatic vs. asymptomatic patients (83% vs. 13%, P = 0.008). Endoscopy also appears to be better at
identifying recurrences amenable to re-treatment with surgery as the recurrences tend to be small and
superficial [15,16] .

In patients with recurrence following treatment for sinonasal malignancy, suspicious findings on
endoscopic examination are often correlated with surveillance imaging and biopsy. The low PPV of
endoscopic examination in asymptomatic patients has been reported to lead to unnecessary biopsies.
Additionally, these unnecessary biopsies can be difficult as a result of tissue inflammation, cerebral spinal
fluid leaks, and osteonecrosis . Studies have found that routine biopsy of asymptomatic patients in the
[17]
setting of normal ear-nose-throat (ENT) examination and endoscopy results in no survival benefit during
the surveillance of sinonasal malignancies .
[18]
Endoscopy plays a particularly important role in the surveillance of patients with a subset of rare sinonasal
malignancies. Patients with SNAC and low-grade SNEC are much more likely to have local recurrence as
[19]
opposed to distant metastases ; as a result, it is particularly important that these patients undergo interval
endoscopy for monitoring disease recurrence. For patients with SNEC, the optimal surveillance strategy
may vary based on tumor grade. Low-grade tumors may be followed with endoscopy, whereas high-grade
tumors, such as the small cell variant, should also be monitored by serial imaging in order to detect distant
metastasis . These recommendations mirror the surveillance guidelines for small cell carcinoma in the
[19]
lung due to a deficiency of prospective studies of surveillance for patients with SNEC. In addition to
sinonasal symptoms, patients with PMM may present with a pigmented lesion on ENT examination that
can be visible on endoscopy. Rarely, a lesion that is nonpigmented may be seen . On exam, PMM macules
[20]
are irregular and asymmetric, which can differentiate PMM macules from melanosis.

IMAGING
Posttreatment surveillance imaging plays an essential role in care of the patient with a sinonasal malignancy.
18
18
Computerized tomography (CT), magnetic resonance imaging (MRI) or F-fluorodeoxyglucose ( FDG)
positron emission tomography (PET)/CT are frequently used in combination, and certain modalities have
been reported to have different advantages. Surveillance imaging for sinonasal malignancies can be
challenging to interpret, given that edema of scarred mucosa following surgical resection and enhancement
near a tissue flap can last for many months after primary treatment . It is important that imaging choices
[21]
encompass all areas of possible recurrence, including all areas of potential distant metastasis, and should
take into account the varying risk of distant metastasis for diverse subtypes of sinonasal malignancies.
Despite the fact that most recurrences are local, studies have shown that imaging frequently diagnoses more
recurrences of sinonasal malignancy than endoscopy alone. As a result, biopsies driven by imaging have
improved sensitivity, accuracy, and PPV compared to biopsies performed solely following suspicious
findings on endoscopy (PPV 72% vs. 43%) [15,16] . However, the utilization of endoscopy to clinically correlate
imaging findings is often useful. Imaging has a high negative predictive value (NPV) in monitoring for
recurrence of sinonasal malignancy (91%) [15,22] . The high NPV suggests that negative surveillance imaging
can be helpful in identifying patients in remission, particularly in the surveillance of asymptomatic patients
without concerning endoscopic findings. The following sections will discuss the different imaging types
used in the surveillance of sinonasal malignancies, highlighting recent advances and unique advantages of
different modalities.