Origin site-based staging system of sinonasal inverted papilloma for application to endoscopic sinus surgery

Endoscopic Removal of Sinonasal Inverted Papilloma Originating From the Posterior Ethmoid Cavity

Sinonasal inverted papilloma is an expansive, benign mass derived from the Schneiderian membrane. It may undergo malignant transformation and most commonly originates from the maxillary sinuses or the lateral walls of the nasal corridors. This case outlines the case of a sinonasal inverted papilloma, which clearly arises from the posterior ethmoid sinus, bordering the skull base. This abnormal originating point was able to be identified during endoscopic excision of the mass and involved mucosa. The ethmoid bone was not resected as it would expose the dura mater, risking CSF leak and complications. This case further supports the use of endoscopy in the investigation of sinonasal inverted papilloma rather than the gold standard approach of lateral rhinotomy. An endoscopic approach allowed for improved safety when accessing the posterior ethmoid cavity. This case also highlights the possibility of novel origins of sinonasal inverted papilloma, such as the membrane of the posterior ethmoid cavity.

Sinonasal inverted papilloma from diagnosis to treatment - a narrative review

Inverted papilloma (IP) is a non-cancerous tumor that develops from the paranasal sinuses. Identifying and diagnosing an IP is vital for an ear, nose and throat specialist, due to its high recurrence rate and ability to transform into malignant carcinoma. Diagnosis is based on endonasal flexible endoscopy, preoperative biopsy, and imaging methods. Treatment is exclusively surgical, and its aim is the complete resection of the tumor to prevent further recurrences. The success of surgery depends on employing the most appropriate surgical technique. The choice should be tailored to the tumor's location, size, and the patient's specific anatomy. Endoscopic, open, or even combined approaches may be considered. Notably, attachment-oriented surgery is the cornerstone in endoscopic endonasal approaches. Regardless of the chosen approach, long-term surveillance is vital, as early detection provides the benefit of easier re-resection.

Challenging Nasal Pathologies: An Inverted Nasal Papilloma Case Series Illustrating Diagnostic Challenges and Management Strategies

The sinonasal inverted papilloma is a benign tumor located in the sinuses lining the nasal cavity. It is a very rare tumor, representing approximately 4% of all sinonasal tumors. The incidence of sinonasal inverted papilloma is higher in males than females and is most commonly diagnosed in the 5th decade of life. Four separate cases of sinonasal pathology involving inverted papillomas are presented in this case series. The first clinical case presents a 68-year-old man with persistent nasal symptoms, who was found to have a sinonasal papilloma, which was successfully removed surgically. In the second case, a 61-year-old woman needed multiple procedures for a comprehensive surgical approach due to her inverted papilloma. Despite postoperative complications, the patient showed improvement at later follow-up appointments. In the third case, a 65-year-old man who had an inverted nasal papilloma previously needed surgery to remove and clear the tumor after developing acute sinusitis and rhinosinusitis symptoms. Last but not least, a 57-year-old male presented with nasal blockage and purulent discharge. Polyps were observed during the examination. The initial biopsy indicated the presence of chronic inflammatory polyps. However, during the operation, a first sample biopsy revealed an inflammatory polyp, but due to the appearance of the mass, the surgeon became suspicious and decided to take another biopsy. The second biopsy confirmed the presence of an inverted nasal papilloma. All things considered, these cases demonstrate clinical variability, difficulties in diagnosing, and effective management techniques related to inverted and sinonasal papillomas. The aim of this case series is to emphasize the importance of proper history taking, physical examination, and use of diagnostic tools to distinctly diagnose inverted nasal papilloma as its symptoms are similar to rhinosinusitis, especially chronic rhinosinusitis.

Bilateral sinonasal inverted papillomas originating from both sides of the frontal sinus and the left lamina papyracea: A case report

RATIONALE

The present investigation documented a case of bilateral sinonasal inverted papilloma (SNIP) that arose from both sides of the frontal sinus and ethmoid sinus. The occurrence of bilateral involvement of the nasal cavities and frontal sinus is rather infrequent.

PATIENT CONCERNS

Informed consent was obtained from the patient.

DIAGNOSIS

Bilateral SNIP.

INTERVENTIONS

The tumor was completely removed by Draf III endoscopic resection complemented by an external eyebrow arch approach, and the postoperative recovery was uneventful.

OUTCOMES

The purpose of this paper is to present a comprehensive reference for the management of bilateral SNIP that affects the frontal sinuses.

LESSONS

This study addresses the staging and surgical management of bilateral SNIP, along with a review of the factors contributing to its recurrence. The recommended treatment method involves applying the Draf III technique combined with an external nasal approach.

Global research on sinonasal inverted papilloma over the past two decades: a bibliometric analysis

Objective

This study aimed to investigate the global research status, hot topics, and prospects in the field of sinonasal inverted papilloma (SNIP) through bibliometric analysis.

Methods

The literature on SNIP was retrieved and downloaded from the Web of Science Core Collection from 2002 to 2021. The bibliometric and visualisation networks of SNIP were constructed using VOSviewer 1.6.18, CiteSpace 6.1. R2, and a bibliometric online analysis platform.

Results

A total of 560 original articles about SNIP research were included, involving 2,457 authors from 610 institutions in 45 countries. The number of SNIP publications showed an overall rising trend, with an average annual output of 28 articles and almost 3 times as many articles published in 2020 as in 2002. The analysis of keyword burst detection indicated that EGFR mutation, malignant transformation and infection are emerging research hotspots. Moreover, EGFR mutation, KRAS mutation, malignant tumour, metallothionein 2a gene, pre-operative diagnosis, HPV-negative tumour, and expression were among the 11 key clusters of co-cited references.

Conclusions

This study provided a comprehensive, systematic, and objective analysis and visualised knowledge map of SNIP over the past 2 decades. In particular, current hotspots and prospective trends in the field of SNIP have been identified. These results highlight the future direction of SNIP research for rhinologists.

Surgical treatment of 186 sinonasal inverted papillomas and analysis of the immunohistochemical and molecular features associated with recurrences

INTRODUCTION

Inverted papillomas (IP) are benign epithelial tumors with a tendency to be locally invasive and with disposition to recur. The aim of our study is to present the results of IP treatment, considering pathological, immunohistochemical and molecular features of recurrence.

MATERIAL AND METHODS

From 1978 to 2020, 186 sinonasal IPs surgeries corresponding to 152 patients were treated in our center. We performed a pathology evaluation of all the recurrent cases reviewing the histological diagnosis, the presence of mixed component other than IP, the koilocytic changes, the p16 over expression and HPV-DNA detection.

RESULTS

Overall recurrence rate was 19 % (35/186). The 35 IP recurrences correspond to 22 patients, 9 of whom presented a single recurrence (single recurrence group) while 13 of them presented more than one recurrence (multi-recurrent group). Immunohistochemical analysis showed a higher percentage of p16 overexpression (54 % vs 33 % p = 0.415) and HPV-DNA presence (23 % vs 0 % p = 0.240) in the multi-recurrent group compared with single recurrence group. In addition, the revision showed more IP with exophytic papilloma focus (38 vs 22 % p = 0.648) and a higher proportion of IP with koilocytotic changes (61 % vs 22 % p = 0.099) in the multirecurrent group. There is no significant difference between groups in our results.

CONCLUSION

The analysis of our patients may differentiate between two groups with recurrent papillomas. A single recurrence group where the cause of recurrence is probably an anatomical problem related to an incomplete resection, and a second pattern, the multi-recurrence group, where HPV infection may be the main cause of recurrence.

Diagnostic strategy and therapeutic management of sinonasal inverted papilloma: our experience with review of literature

Background

The sinonasal inverted papilloma is a rare benign tumor, characterized by local aggressiveness, a high rate of recurrence after surgical resection, and the possibility of malignant transformation. The aims of this study are to analyze diagnostic strategy and therapeutic modalities and to evaluate results after surgery.

Methods

We report a retrospective study, including patients operated for inverted sinonasal papilloma in our department. Preoperatively, all patients were assessed by CT scan (computed tomography), 9 of them by MRI (magnetic resonance imaging).

Results

The average age of our patients was 52 years with a male predominance. The most common symptom was unilateral nasal obstruction. The endoscopic appearance was suggestive of inverted papilloma (IP) in 75% of cases. Thirty-two patients underwent an exclusive endonasal endoscopic surgery; one patient was operated with a combined approach. Two patients underwent external approaches. A recurrence was observed in 4 patients (11%).

Conclusion

Preoperative investigation for IP is essentially based on MRI, also required in case of recurrence. Histological examination of the entire tumor is crucial to rule out an associated carcinoma. The “all endoscopic” management is not always achievable for these tumors.

Surgical treatment of sinonasal inverted papilloma

PURPOSE OF REVIEW

To highlight how surgery of inverted papilloma has developed during the past year. Moreover, to give our own opinion on the state of research regarding inverted papilloma surgical management.

RECENT FINDINGS

Recent studies covering surgical treatment of inverted papilloma concentrated on the optimum surgical management aiming at complete resection, least morbidity and best outcome, with special interest regarding the maxillary and frontal sinuses. In maxillary sinus inverted papilloma, to avoid empty nose and/or epiphora, recent articles exerted all attempts to preserve the integrity of both the inferior turbinate and nasolacrimal duct, yet offer best exposure of all maxillary sinus walls specially the anterior and inferior ones. These included the new modifications of the prelacrimal and Denker approaches and lateral nasal wall transposition. In frontal sinus inverted papilloma, to avoid an external approach and insure postoperative patency of frontal sinus ostium, the periorbital suspension was introduced and orbital transposition approach was comprehensively utilized especially in far lateral located lesions and/or in supraorbital recess involvement. Associated malignancy is an important issue to identify as management plans significantly differ. Recurrence occurs early within the first 2 years but long-term follow-up is mandatory.

SUMMARY

Surgical procedures of sinonasal inverted papilloma are planned according to origin rather than the tumor extent. Origin targeted surgery and proper management of the site of attachment are the key to achieve complete surgical resection of sinonasal inverted papilloma. Recent trends advise the least destructive surgical techniques that offer best exposure, complete excision SNIP and least recurrence.

Endoscopic Modified Medial Maxillectomy for Inverted Papilloma of the Maxillary Sinus

BACKGROUND

Sinonasal inverted papilloma (SNIP) is a benign tumor that can be surgically managed by an endoscopic approach. However, SNIP has a high recurrence rate, mainly due to incomplete resection.

AIM

This study aimed to analyze the outcomes of endoscopic modified medial maxillectomy in treating SINP originating from the maxillary sinus.

METHODS

The authors retrospectively analyzed 24 patients treated for SNIP via endoscopic modified medial maxillectomy at our institution between August 2014 and June 2019. During surgery, the mucosa involved in the tumor was stripped, and the bone underlying the tumor base was completely excised. Demographic data, surgical technique, location of SNIP attachment, complications, follow-up duration, and recurrence were recorded.

RESULTS

Twenty four patients with SNIP were identified (16 males). All patients had Krouse stage-III disease. Eleven patients presented with single attachment and 13 with multiple attachments. None of the patients had any complications during surgery. Four patients had postsurgical facial numbness around the cheek and upper lip. After a mean follow-up of 35.12 ± 14.98 months, no recurrence of SNIP was observed.

CONCLUSIONS AND SIGNIFICANCE

Endoscopic modified medial maxillectomy is a safe and effective technique for treating SNIP. Recurrence can be reduced by complete excision of the attachment sites.

Comparison of MRI and CT in the Evaluation of Unilateral Maxillary Sinus Opacification

Objectives

To evaluate the diagnostic performance of MRI compared with CT in differentiating neoplastic from infectious/inflammatory causes of complete unilateral maxillary sinus opacification (UMSO). Although MRI is increasingly used, no studies validate its utility compared to CT or nasal endoscopy in this context.

Methods

A retrospective analysis of 49 patients presenting with complete UMSO to a tertiary referral centre was performed, investigated with both CT and MRI. Two head and neck radiologists independently reviewed each imaging modality and recorded both a final diagnosis and Likert-scale diagnostic certainty score. A consensus radiological diagnosis was determined, stratified into potentially neoplastic or infectious/inflammatory aetiology, and compared with nasal endoscopy and final diagnosis. Diagnostic performance and interoperator agreement for predicting neoplasia were calculated.

Results

Both CT and MRI demonstrated high sensitivity and negative predictive value for neoplasm, although MRI was more specific (79%; 95% CI: 60–92%) than CT (14%; 95% CI: 4–32%), with a higher positive predictive value. MRI was more accurate (88%; 95% CI: 75–95%) than CT (49%; 95% CI: 34–64%) in diagnosing neoplasia. MRI had significantly higher diagnostic certainty Likert scores than CT (p < 0.0001 for both observers). Interobserver agreement was fair for CT (kappa coefficient = 0.327) and excellent for MRI (kappa coefficient = 0.918).

Conclusions

MRI is more specific than CT in characterising UMSO, with greater diagnostic certainty and reproducibility. The additive diagnostic value of MRI complements CT, potentially reducing diagnostic delays in some cases and the need for diagnostic endoscopic sinus surgery in others. We recommend MRI incorporation into the diagnostic pathway for patients with UMSO.

Outcomes of sinonasal oncocytic papilloma by endoscopic approach in 69 patients

OBJECTIVE

Sinonasal oncocytic papilloma (SOP) is a rare subtype of sinonasal papilloma. There are currently few reports on its clinical features and outcomes after endoscopic surgical resection. This study aims to explore the clinical characteristics of SOP and potential factors predicting tumor recurrence through a single-center retrospective case series analysis.

METHODS

We conducted a retrospective analysis of 69 patients who underwent endoscopic surgery of SOP from June 2012 to April 2019. The data of patients' demographics, clinical features, follow-up period, and treatment outcomes were collected.

RESULTS

The series includes 43 males and 26 females with an average age of 60.2 years. The tumor commonly involved the nasal cavity (n = 59; 89.4%), followed by maxillary sinus (n = 31; 44.9%), ethmoid sinus (n = 28; 40.6%), frontal sinus (n = 6; 8.7%) and sphenoid sinus (n = 6; 8.7%). The follow-up period ranged from 3 months to 96 months (mean, 34.6 months) and nine patients (13%) developed tumor recurrence during the follow-up period. Univariate analysis found that the recurrence of SOP was significantly related to tumor attachment site, Oikawa tumor stage, and histological dysplasia (p<0.05). Multivariate COX regression analysis found that Oikawa staging system (p = 0.024) and presence of dysplasia (p = 0.04) were significantly related to tumor recurrence.

CONCLUSION

SOP had low recurrence rate which was comparable to sinonasal inverted papilloma in the endoscopic era. Our findings also demonstrated that presence of dysplasia is an independent prognostic factor for recurrence free survival.

Attachment-Oriented Endoscopic Treatment of Inverted Papilloma Involving the Frontal Sinus/Recess

PURPOSE

Sinonasal inverted papilloma (IP) is a benign but locally aggressive tumor for which an endoscopic or external surgical approach is the treatment of choice. Complete resection of IP involving the frontal sinus/recess forms one of the most challenging procedures in the field of sinonasal surgery. This study aims to present our experience in the management of extensive frontal sinus IP based on the attachment sites of the tumor.

METHODS

Thirteen patients with IP involving the frontal sinus/recess between 2010 and 2018 were presented. The data collected include demographic data, tumor attachment sites, tumor extension, tumor staging according to Meng's staging system, surgical approach, recurrence, and follow-up.

RESULTS

The patients were successfully treated by endoscopic surgery without any additional external approaches. The attachment sites of the IP were multifocal in some patients. No recurrence was identified after an average follow-up period of 52.88 months. No major intra- or postoperative complications were observed.

CONCLUSION

The present study shows that attachment-oriented excision for IP involving the frontal sinus/recess is an acceptable approach. Surgeons should select the surgical approach based on the attachment sites of the tumor rather than the extension of the tumor. Even more importantly, the tumor attachment sites should include the sites of adhesion to the bone wall and the site of origin.

Dynamic Contrast-Enhanced MRI Can Quantitatively Discriminate the Original Site From Peripheral Portion of Sinonasal Inverted Papillomas

BACKGROUND

Identification of the original site of sinonasal inverted papillomas (SIPs) is difficult but essential for reducing the recurrence rate. Dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) may provide information about tissue perfusion and permeability to solve this problem.

PURPOSE

To investigate the accuracy of DCE-MRI parameters in discriminating between regions of interest (ROIs) in the original site and peripheral portion.

STUDY TYPE

Retrospective.

POPULATION

Ninety consecutive patients with pathologically proven SIP.

FIELD STRENGTH/SEQUENCE

3.0T/DCE-MRI using fast-spoiled gradient recalled (FSPGR) T₁ -weighted images with fat saturation.

ASSESSMENT

ROIs were placed in the original site and the peripheral portion of SIP by two radiologists according to surgical records. Maximum slope of increase (MaxSlope), contrast-enhancement ratio (CER), bolus arrival time (BAT), initial area under the signal intensity-time curve (IAUGC), volume transfer constant (K^trans ), volume of the extravascular extracellular space (v_e ), and rate constant (K_ep ) were calculated and repeated again with a month interval by a radiologist.

STATISTICAL TESTS

Univariate and multivariate analysis was used to determine the best diagnostic parameters, and their performances in discrimination were evaluated by receiver operating characteristic (ROC) curves. Reproducibility was estimated by the intraclass correlation coefficient (ICC).

RESULTS

MaxSlope, CER, IAUGC, K^trans , and v_e were significantly lower (P < 0.05) in the original site than the peripheral portion of SIPs. CER (odds ratio [OR] = 0.227, 95% confidence interval [95% CI] = 0.073-0.704) and v_e (OR = 0.048, 95% CI = 0.004-0.527) were the best indicators for identifying the original ROIs. The combination of CER and v_e had the best diagnostic performance in the discrimination between the ROIs (the area under the curve [AUC]: 0.937; 95% CI: 0.896-0.974).

DATA CONCLUSION

DCE-MRI derived parameter values differed between the original site and the peripheral portion of SIPs. The model combining CER and v_e appears to be able to accurately distinguish the original from peripheral ROIs.

LEVEL OF EVIDENCE

4 TECHNICAL EFFICACY STAGE: 2.

Need for long-term follow-up in sinonasal inverted papilloma: A Single-institution experience

BACKGROUND

Most studies on sinonasal inverted papillomas (SNIPs) regarding risk factors for recurrence, recurrence rates (RRs) and malignant transformation are biased by a significant proportion of revision cases.

METHODS

Retrospective study on patients with consecutive, treatment-naïve SNIPs at a tertiary referral center between 1999 and 2019.

RESULTS

Overall, RR was 9.8% (10 of 102 patients), with 2 of 10 recurrences (20%) occurring after more than 5 years. Histopathological workup revealed synchronous malignancy in 2 of 102 patients (2%). Subgroup analysis revealed a significantly higher RR for SNIPs involving the frontal sinus (26.3% vs 6.0%, P = .02). No SNIPs primarily originating from the frontal sinus were observed.

CONCLUSION

Overall, RR of treatment-naïve SNIPs is comparably low; however, long-term follow-up is mandatory due to late recurrences. Secondary involvement of the frontal sinus was identified as risk factor for recurrence. No SNIPs primarily originating from frontal sinus were observed.

Comparison of Current Staging Systems for Sinonasal Inverted Papilloma

Background

A staging system is essential for determining the optimal surgical approach and predicting postoperative outcomes for inverted papilloma (IP). Although staging systems based on the extent to which the location is occupied by an IP have been widely used, an origin site-based classification of IP using unsupervised machine learning algorithms has recently been reported.

Objective

To determine the most appropriate of five staging systems for sinonasal IP by comparing recurrence rates for each stage according to each of those systems.

Methods

Eighty-seven patients with sinonasal IP were enrolled in the study. Their tumors were retrospectively categorized according to the Krouse, Oikawa, Cannady, and Han staging systems, which are based on the extent of IP, and the Meng system, which is based on the site of origin. The rates of recurrence for each stage of the five systems were compared.

Results

Seven of the 87 patients (8.0%) had recurrences during an average 45.5 months (12–138 months) of follow-up. There were significant differences in disease-free survival between the stages specified by Han and Meng (p = 0.027 and p < 0.001, respectively), but not between the stages specified by Krouse, Oikawa, and Cannady (p = 0.236, 0.062, and 0.130, respectively). Cox proportional hazard models revealed that Meng system (adjusted hazard ratio [aHR] 4.32, 95% confidence interval [CI] 1.10–17.04) and presence of dysplasia (aHR 7.42, 95% CI 1.15–47.85) were significantly associated with recurrence.

Conclusion

The staging systems proposed by Han and Meng were found to be accurate in terms of tumor recurrence. We recommend use of the Han staging system before surgery and the Meng system after intraoperative identification of the origin of the tumor.

Does evaluation of tumor volume or/both origination site better guide to optimal surgery for inverted papilloma?

INTRODUCTION

Sinonasal inverted papilloma is noted for its high rate of recurrence. Staging systems aid to reduce recurrence and avoid excessive surgeries by guiding the selection of the optimal surgical approach.

OBJECTIVE

To evaluate the effectiveness of different endoscopic approaches in inverted papilloma by assessing tumor origin site and tumor volume.

METHODS

Krouse classification system that is based on tumor volume was used for staging; furthermore, tumor origin sites were grouped as lateral nasal wall, medial wall and other walls of maxillary sinus. The main treatment method for all patients was endoscopic sinus surgery. Endoscopic extended middle meatal antrostomy, endoscopic Caldwell-Luc and endoscopic medial maxillectomy were the additional surgery types performed in different combinations.

RESULTS

Fifty-five patients (42 male) with a mean 54.9±14.4 years of age were included. 37 patients were diagnosed with advanced stage inverted papilloma (67.2 %). Recurrence was observed in 12 patients (21.8 %). In early stage lateral nasal wall origination, no recurrence was observed in the simple tumor resection group (0/10). In early stage medial wall origination, no recurrence was observed in the extended middle meatal antrostomy group (0/8). In advanced stage medial wall origination, the recurrence rates of extended middle meatal antrostomy, extended middle meatal antrostomy+endoscopic Caldwell- Luc and endoscopic medial maxillectomy were 100.0 %, 53.8 % and 13.6 %, respectively (p=0.002). In advanced stage other walls of maxillary sinus origination, recurrence rates of extended middle meatal antrostomy+endoscopic Caldwell-Luc and endoscopic medial maxillectomy were 20 % and 16.6 %, respectively (p=0.887).

CONCLUSION

Tumor origin site, tumor stage and surgery types show an impact on recurrence. Despite the fact that tumor origin site singly could lead to appropriate selection of the surgery type in most cases, tumor stage carries substantial importance in selection of surgery type for sinonasal-inverted papilloma. An operation plan regarding both tumor volume and tumor origin site may aid surgeons in selecting optimal endoscopic surgical method to avoid recurrence or excessive surgeries.

Sinonasal inverted papilloma: rate of recurrence and malignant transformation in 44 operated patients

Introduction

Although sinonasal inverted papillomas are benign lesions, they are locally aggressive and have a potential malignant transformation ranging from 5% to 15%, with a high recurrence rate.

Objective

The aim of this article is to describe the rate of recurrence and malignant transformation in patients with a diagnosis of inverted papilloma who underwent surgery in a tertiary hospital in São Paulo.

Methods

We performed a retrospective analysis of patients diagnosed with sinonasal papilloma who had undergone surgery in a tertiary hospital in São Paulo, between August 1998 and August 2017. A patient chart review was conducted to assess data of patients’ demographics, tumors characteristics, follow-up appointments, recurrence and malignancy. Inverted papillomas were analyzed and classified under the Krouse staging system.

Results

A total of 69 surgeries were performed in patients with diagnosis of sinonasal papilloma. Inverted papilloma was the most prevalent subtype (49 cases ‒ 80.33%), followed by exophytic papilloma (6 cases ‒ 9.84%) and by oncocytic papilloma (6 cases – 9.84%). The recurrence rate was 34.09% for inverted papilloma (15/44) and the mean time of recurrence was 24.6 months. Malignant transformation occurred in 6 patients (13.64%). Three of these patients presented carcinoma in the first surgery and three patients developed carcinoma during the follow-up.

Conclusion

The high recurrence rate and malignancy potential allow us to consider inverted papillomas as aggressive tumors. In a tertiary hospital in São Paulo the recurrence rate the mean time to recurrence is 24.6 months. The recurrence after 10 years implies was 34.09% and the need for long-term follow up. It is possible that the high recurrence rate and the high malignant transformation rate we found are due to the large number of tumors discovered at an advanced stage (most of them staged T3 and T4), secondary to poor access to health system, in developing countries.

Origin site-based staging system of sinonasal inverted papilloma for application to endoscopic sinus surgery

Background

We aimed to assess the recurrence risk of sinonasal inverted papillomas (SNIPs), based on a staging system developed according to the originating site of SNIP.

Methods

A total of 200 patients with SNIP were enrolled, and a staging system was developed based on the originating sites and corresponding recurrence rates of tumor in the patients. In the verification phase, 675 patients with SNIPs were enrolled as above, and the originating sites of the SNIPs were confirmed by an endoscopic sinus surgery. Cluster analysis was performed to determine the stage for each SNIP.

Results

Overall, 608 patients completed the study. SNIP recurrence rates for stages 1‐4 were 0 (n = 43), 4.0% (n = 420), 13.4% (n = 134), 36.4% (n = 11), respectively (total = 6.4%).

Conclusions

The origin site‐based classification of SNIP may aid surgeons in selecting appropriate endoscopic surgical approaches to minimize the risk of recurrence.