Imaging Features of Sinonasal Inverted Papilloma: A Pictorial Review

[Inverted papilloma of the nose and paranasal sinuses : Diagnosis, treatment, and malignant transformation]

Inverted papilloma (IP) are benign tumors that show a locally aggressive behavior, a high rate of recurrence, and a potential for malignant transformation. Specific radiological signs such as hyperostosis at the origin of the IP and convoluted cerebriform patterns, as well as the typical endoscopic aspect, can lead to diagnosis and enable preoperative planning of surgical access and the extent of surgery. Endonasal endoscopic techniques are considered the gold standard and the introduction of extended surgical techniques such as the prelacrimal approach, frontal drillout, or orbital transposition facilitate complete subperiosteal resection with preservation of important physiological structures. There is a risk of synchronous and metachronous squamous cell carcinomas (IP-SCC). Research focuses on radiological criteria to differentiate benign IP from IP-SCC, genetic and epigenetic factors in the process of malignant transformation, and estimation of the risk of IP progressing to IP-SCC.

Multiparametric MRI-based radiomics nomogram for predicting malignant transformation of sinonasal inverted papilloma

AIM

To investigate the feasibility of a radiomics nomogram model for predicting malignant transformation in sinonasal inverted papilloma (IP) based on radiomic signature and clinical risk factors.

MATERIALS AND METHODS

This single institutional retrospective review included a total of 143 patients with IP and 75 patients with IP with malignant transformation to squamous cell carcinoma (IP-SCC). All patients underwent surgical pathology and had preoperative magnetic resonance imaging (MRI) and computed tomography (CT) sinus studies between June 2014 and February 2022. Radiomics features were extracted from contrast-enhanced T1-weighted images (CE-T1WI), T2-weighted images (T2WI), and apparent diffusion coefficient (ADC) maps. The least absolute shrinkage and selection operator (LASSO) were performed to select the features extracted from the sequences mentioned above. Independent clinical risk factors were identified by multivariate logistic regression analysis. Radiomics nomogram was constructed by incorporating independent clinical risk factors and radiomics signature. Based on discrimination and calibration, the diagnostic performance of the nomogram was evaluated.

RESULTS

Twelve radiomics features were selected to develop the radiomics model with an area under the curve (AUC) of 0.987 and 0.989, respectively. Epistaxis (p=0.011), T2 equal signal (p=0.003), extranasal invasion (p<0.001), and loss of convoluted cerebriform pattern (p=0.002) were identified as independent clinical predictors. The radiomics nomogram model showed excellent calibration and discrimination (AUC: 0.993, 95% confidence interval [CI]: 0.985-1.00 and 0.990, 95% CI: 0.974-1.00) in the training and validation sets, respectively.

CONCLUSION

The nomogram that the combined radiomics signature and clinical risk factors showed a satisfactory ability to predict IP-SCC.

International Consensus Statement on Allergy and Rhinology: Sinonasal Tumors

BACKGROUND

Sinonasal neoplasms, whether benign and malignant, pose a significant challenge to clinicians and represent a model area for multidisciplinary collaboration in order to optimize patient care. The International Consensus Statement on Allergy and Rhinology: Sinonasal Tumors (ICSNT) aims to summarize the best available evidence and presents 48 thematic and histopathology-based topics spanning the field.

METHODS

In accordance with prior International Consensus Statement on Allergy and Rhinology documents, ICSNT assigned each topic as an Evidence-Based Review with Recommendations, Evidence-Based Review, and Literature Review based on the level of evidence. An international group of multidisciplinary author teams were assembled for the topic reviews using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses format, and completed sections underwent a thorough and iterative consensus-building process. The final document underwent rigorous synthesis and review prior to publication.

RESULTS

The ICSNT document consists of four major sections: general principles, benign neoplasms and lesions, malignant neoplasms, and quality of life and surveillance. It covers 48 conceptual and/or histopathology-based topics relevant to sinonasal neoplasms and masses. Topics with a high level of evidence provided specific recommendations, while other areas summarized the current state of evidence. A final section highlights research opportunities and future directions, contributing to advancing knowledge and community intervention.

CONCLUSION

As an embodiment of the multidisciplinary and collaborative model of care in sinonasal neoplasms and masses, ICSNT was designed as a comprehensive, international, and multidisciplinary collaborative endeavor. Its primary objective is to summarize the existing evidence in the field of sinonasal neoplasms and masses.

Clinical outcomes of sinonasal inverted papilloma: a retrospective analysis of 139 cases

OBJECTIVES

Sinonasal inverted papilloma has a high tendency for recurrence, local bone destruction and risk of malignant transformation. Therefore, complete resection of the tumour is required, and close follow up is essential. This article describes the clinical outcomes, recurrence rate and malignant transformation rate of sinonasal inverted papilloma.

METHODS

In this study, 139 patients diagnosed with sinonasal inverted papilloma in our hospital from December 2010 to May 2022 were retrospectively analysed. All patients underwent endoscopic surgery.

RESULTS

Sinonasal inverted papilloma occurred more often in males than in females. The mean age of patients with sinonasal inverted papilloma was 67.3 ± 5.7 years at diagnosis. The most prevalent site of origin was the maxillary sinus (50.4 per cent). The recurrence rate was 5.75 per cent, and the malignant transformation rate was 6.5 per cent.

CONCLUSION

All patients in this study underwent endoscopic surgery. Meticulous resection and regular long-term follow ups are crucial to reducing sinonasal inverted papilloma recurrence after surgery.

Malignant and Nonmalignant Sinonasal Tumors

Sinonasal tumors are rare, diverse, complex lesions with overlapping demographic and clinical features. Malignant tumors are more common, with a grave prognosis, and require biopsy for accurate diagnosis. This article briefly reviews the classification of sinonasal tumors and provides imaging examples and imaging characteristics of each clinically important nasal and paranasal mass lesions. Although there are no true pathognomonic imaging features, it is important for the radiologist to have a broad knowledge of the various CT and MR imaging findings that can help narrow the differential diagnosis and aid in early diagnosis and mapping of tumor for treatment planning.

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.

Sinonasal Inverted Papilloma Showing a Misleading Finding on Magnetic Resonance Imaging

Sinonasal inverted papilloma (IP) is the most common benign tumor in sinonasal cavities. Treatment involves excising the whole tumor, so it is essential to evaluate the extent of the tumor by preoperative radiographic findings. Magnetic resonance imaging (MRI) is superior to computed tomography (CT) for determining a tumor's location as MRI can discern the difference between mucus and IP. We herein report a 51-year-old man with sinonasal IP treated with endoscopic sinus surgery (ESS). Preoperative MRI showed findings resembling a convoluted cerebriform pattern on T2-weighted imaging, but this site was not enhanced by intravenous gadolinium at all. We preoperatively suspected that this site was not part of the tumor but rather the accumulation of mucus, and indeed, we found no tumor at this site when we performed the surgery. This patient is a valuable example of misleading findings of IP on T2-weighted imaging and underscores the importance of contrast-enhanced T1-weighted imaging to determine the extent of IP.

Case Report: Oncocytic Schneiderian Papilloma Originating From the Sphenoid Sinus

A rare case of oncocytic Schneiderian papilloma originating from the sphenoid sinus characterised, for 3 years, by non-specific symptoms of severe headache, a block of nasal breathing, and deprecating sense of smell was presented by an elderly female patient. Sphenoid sinus functional endoscopic sinus surgery (FESS), with a one-block tumour excision, through an endonasal approach, with a histological study of removed tumour masses, were performed on the patient. Long observation in the post-operative period was necessary, considering the risk of recurrence and malignancy of oncocytic Schneiderian papilloma (OSP). Although the oncocytic papilloma of the sphenoid sinus is rare, non-specific symptoms make this pathology easily misdiagnosed. Thus, any isolated unilateral process in the paranasal sinuses with long-existing symptoms must be given careful attention due to the chance of this process being an inverted papilloma with malignization. CT scan indicating a unilateral opacification of paranasal sinuses with local calcifications is a typical manifestation, and endoscopic sphenoidotomy can be recommended as a treatment of choice.

Preoperative Prediction of Malignant Transformation of Sinonasal Inverted Papilloma Using MR Radiomics

Purpose

Accurate preoperative prediction of the malignant transformation of sinonasal inverted papilloma (IP) is essential for guiding biopsy, planning appropriate surgery and prognosis of patients. We aimed to investigate the value of MRI-based radiomics in discriminating IP from IP-transformed squamous cell carcinomas (IP-SCC).

Methods

A total of 236 patients with IP-SCC (n=92) or IP (n=144) were enrolled and divided into a training cohort and a testing cohort. Preoperative MR images including T1-weighted, T2-weighted, and contrast enhanced T1-weighted images were collected. Radiomic features were extracted from MR images and key features were merged into a radiomic model. A morphological features model was developed based on MR morphological features assessed by radiologists. A combined model combining radiomic features and morphological features was generated using multivariable logistic regression. For comparison, two head and neck radiologists were independently invited to distinguish IP-SCC from IP. The area under the receiver operating characteristics curve (AUC) was used to assess the performance of all models.

Results

A total of 3948 radiomic features were extracted from three MR sequences. After feature selection, we saved 15 key features for modeling. The AUC, sensitivity, specificity, and accuracy on the testing cohort of the combined model based on radiomic and morphological features were respectively 0.962, 0.828, 0.94, and 0.899. The diagnostic ability of the combined model outperformed the morphological features model and also outperformed the two head and neck radiologists.

Conclusions

A combined model based on MR radiomic and morphological features could serve as a potential tool to accurately predict IP-SCC, which might improve patient counseling and make more precise treatment planning.

Left-sided facial mass in an adult female

A left maxillary sinus soft tissue mass was discovered on computed tomography in a 70-year-old woman who had been experiencing blood-tinged mucus for 2 years. The lesion demonstrated mild enhancement, and bony destruction. Magnetic resonance imaging displayed a cerebriform appearance of the mass, which mimicked the appearance of inverted papilloma. However, histology and staining identified the lesion as ameloblastoma. Resection of the tumor was successful with no recurrence 1 month later on follow-up computed tomography. This case represents an unusual imaging presentation of ameloblastoma, and an opportunity to avoid the misdiagnosis of inverted papilloma in similar future cases.

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.

[Unilateral diseases of the maxillary sinus]

Unilateral diseases of the maxillary sinus are among the most common rhinologic diagnoses. The diversity of these diseases can represent a challenge for the treating physician. The spectrum ranges from harmless maxillary sinus cysts that seldom require treatment, to highly aggressive malignant tumors. Special attention should be given to the management of inverted papilloma. These benign tumors are characterized by high recurrence rates and the potential for malignant transformation. The key to minimizing recurrence is precise surgical intervention. Other unilateral maxillary sinus diseases such as the antrochoanal polyp and the fungus ball (aspergilloma) are also discussed in depth.

Clinical evidence based review and systematic scientific review in the identification of malignant transformation of inverted papilloma

Background

Inverted papilloma (IP) is an unusual type of benign tumor that has high recurrence rates and the potential to transform into squamous cell carcinomas (SCC). The mechanism of the transformation process from IP to IP-SCC is uncertain and there is no consensus regarding the best practice for IP-SCC detection. The goal of this study is to identify the best clinical methods to detect for IP-SCC.

Methods

An evidence-based review was performed using Medline and Ovid to obtain all articles up to October 10th, 2019 pertaining to identification of IP malignant transformation. All manuscripts discussing clinical methods or biomarkers were included.

Results

Based on clinical research studies, convoluted cerebriform pattern and apparent diffusion coefficient values on Magnetic Resonance Imaging (MRI) can help differentiate benign IP from SCC and increased SUVmax on PET/CT is associated with higher probability of malignancy although not as specific. No consensus about the best biomarker for IP-SCC has been reached among researchers and continues to be exploratory.

Conclusion

Endoscopy with biopsy is the gold standard practice to identify IP-SCC; however, MRI is the preferred imaging modality to recognize malignant transformation in cases where biopsy is difficult. Multiple biomarkers have shown positive results, but no single indicator with clinical significance for monitoring malignant transformation process has been found.

How aggressive should resection of inverted papilloma be? Refinement of surgical planning based on the 25-year experience of a single tertiary center

BACKGROUND

The technique for transnasal endoscopic resection of inverted papilloma (IP) has evolved considerably during the last 20 years. The aim of the present study is to retrospectively analyze a single tertiary center series, with special emphasis on assessing the value of an "insertion-driven" technique on local control.

METHODS

Patients undergoing endoscopic resection for IP at the University of Brescia during the period 1991 to 2015 were enrolled. Site of origin and extension of IPs were assessed, together with presence of dysplasia and carcinoma in situ. Patients were divided in 3 cohorts: (1) historical cohort (treated before 2008), (2) contemporary "centripetal" cohort (treated with a traditional technique after 2008), and (3) contemporary "insertion-driven" cohort (treated with insertion-driven resection). Groups were compared considering outcomes and complications.

RESULTS

The series included 210 patients. Mean follow-up was 77.8 months. Thirty-eight (18.1%) patients showed precancerous changes. Maxillary involvement (p = 0.021) and presence of precancerous changes (p = 0.013) were significantly associated with a higher risk of recurrence. Five-year local control rate before and after 2008 was 95.1% and 90.5%, respectively. The insertion-driven cohort was associated with lower disease control when IPs involved the maxillary sinus. The rate of complications was 11.9%. The insertion-driven cohort was associated with a lower rate of major complications (p = 0.098).

CONCLUSION

Preoperative evidence of precancerous changes and/or involvement of maxillary sinus should prompt the surgeon to address the disease more aggressively (centripetal resection). Preoperative imaging and biopsy with abundant material may optimize the chance to stratify patients eligible for less or more conservative approaches.

Invasive squamous cell carcinoma arising in an inverted papilloma involving oral cavity

Inverted papilloma (IP) is a benign tumour characterized by the growth of epithelial cells downward into the underlying supportive tissue. The tumour derives from the lining mucosa of the nasal cavity and paranasal sinuses. IP typically arises as a unilateral lesion from the lateral wall of the nasal cavity and extends secondarily to the paranasal sinuses. The aggressive behaviour of IP causing local invasion, its tendency for local recurrence, and its propensity to be associated with carcinoma constitute serious complications. This paper describes a very rare case of IP associated with squamous cell carcinoma, extending into paranasal sinuses, causing destruction of the bony wall of maxillary sinus and involvement of the oral cavity.

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.

Imaging review of the anterior skull base

The anterior skull base (ASB) is intimately associated with the unique soft tissue subtypes of the nasal cavity, paranasal sinuses, orbits, and intracranial compartment. Pathology involving the ASB is rare but the causes are manifold and can be broadly subdivided into those intrinsic to the skull base and processes extending from below or above. Sinonasal pathology is the most commonly encountered and poses significant management challenges that rely heavily on accurate interpretation of the radiological findings. We illustrate the normal anatomy of the ASB and present a cross-sectional imaging review of the pathological entities that may be encountered, focusing on the specific features that will impact on clinical and surgical management.

Imaging Sinonasal disease with MRI: Providing insight over and above CT

This article illustrates and discusses the applications and value of magnetic resonance imaging (MRI) in the evaluation of sinonasal disease. There are several clinical scenarios where MRI can add value over conventional computed tomography (CT) evaluation of the sinonasal spaces. Specifically, MRI can provide insight through better depiction of the anatomy of certain sinonasal sub-sites including the olfactory structures. It can aid in evaluating anosmia, sinusitis (fungal sinusitis and complications), benign and malignant lesions, CSF leaks and pathology extending into sinonasal spaces.

Respiratory Epithelial Adenomatoid Hamartomas: An Increasingly Common Diagnosis in the Setting of Nasal Polyps

Background

Respiratory epithelial adenomatoid hamartomas (REAH) are benign nose neoplasms found in the nasal cavity and sinuses. Symptoms include anosmia, nasal obstruction, facial pressure, and rhinorrhea. Although previously thought to be rare, these tumors are being increasingly recognized on pathology in patients undergoing endoscopic sinus surgery. However, REAH is difficult to diagnose before surgery because it may mimic other entities, such as nasal polyps or inverted papilloma, and is often found incidentally only after surgery.

Objective

The aims of this study were to (1) add an additional case series of REAH to the literature, (2) report unique imaging findings on computed tomography and magnetic resonance imaging, and (3) pool and summarize all available data from existing publications.

Methods

Retrospective chart review from years 2004 to 2015 and a literature review

Results

Twenty-three cases were found in our case series, which included 12 men (52%) and 11 women (48%), with a mean age of 59 years. No cases were found before 2007. Lund-Mackay scores were comparable with those found in chronic rhinosinusitis without nasal polyposis. Imaging consistently demonstrated a discoid-shaped mass at the olfactory cleft. Fifty previous publications were found (4 prospective, 11 retrospective studies, 9 case series, 26 cases reports), which included 660 patients diagnosed with REAH. Pooled data revealed a mean age of 54 years (range, 9–86 years) and a male to female ratio of 3:2.

Conclusion

The results of our study further refined the average age at which REAH diagnosis occurs as 54 years old, although it may occur at any age. There is a clear male-to-female predominance (3:2). In addition, olfactory cleft widening and discoid soft tissue at the olfactory cleft are hallmark radiographic findings. The vast majority of published cases occurred during the past 4 years, which indicated increased recognition of REAH.