Introduction
Benign inflammatory nasal polyps are often diagnosed based on their distinctive clinical features: single or multiple, pale or grey polypoid growth.Reference Newton and Ah-See1 They are usually bilateral and often arise from the middle meatus. Unilateral nasal polyps raise the possibility of a benign or malignant neoplasm. They may also represent a meningocele, particularly if medial to the middle turbinate.Reference Ziade, Hamadan, Homsi, Kazan and Hadi2
In general, patients with benign-appearing unilateral nasal polyps should undergo a computed tomography (CT) scan of the paranasal sinuses to evaluate disease extent and investigate for features that may indicate an alternate diagnosis, such as bony destruction, while also checking for mixed density or intralesional calcification, and checking dentition to evaluate for odontogenic causes.
Patients with unilateral nasal polyps and no suspicious clinical or radiological features usually undergo diagnostic polypectomy with or without concomitant functional endoscopic sinus surgery (FESS). Routine histological assessment for all unilateral nasal polyps is generally advised; however, there may be potential to manage some cases conservatively.
This study aimed to: determine the incidence of significant pathology in patients presenting with benign-appearing unilateral nasal polyps, and further characterise the condition, in order to inform current practice and guidance in the management of benign-appearing unilateral nasal polyps.
Methods
This was a retrospective observational study. Patients were identified using operating theatre procedure codes for a nasal polypectomy. We included all consecutive adult patients who underwent nasal polypectomy, with or without FESS, for benign-appearing unilateral nasal polyps, over a 13-year period (January 2008 to January 2021), at Sheffield Teaching Hospitals. We excluded patients who presented with clinically suspicious polyp(s) on clinical assessment (n = 12) and those who had undergone revision polypectomy (n = 3).
A unilateral polyp(s) was defined as the presence of nasal polyp(s) on one side, with the absence of polyps on the contralateral side on examination. Unilateral nasal polyps with no clinical suspicious features of malignancy on clinical assessment, and with classical appearance of inflammatory polyps, were considered to be ‘benign-appearing inflammatory nasal polyps’.
Data were collected on the following variables: patients’ demographics, clinical presentation details, nasal endoscopy findings, imaging findings, operative details and histopathological diagnosis.
A standardised data collection sheet was used to extract information from electronic case notes. In cases where information was missing or incomplete, paper notes were retrieved for clarity. Missing data were excluded from the analysis. SPSS® statistical software version 25 was used to analyse data. Categorical data were presented as frequency and percentage. Continuous data were presented as median and interquartile range. No inferential statistical test was performed.
Approval for the study was obtained from the hospital's Clinical Effectiveness Unit (reference number: 9870). Ethical approval was not needed, as the study design was retrospective, and involved no change to patient care or services.
Results
A total of 77 patients were included in the study. There were 32 (42 per cent) females and 45 (58 per cent) males. The mean (standard deviation) age was 52 (18.4) years. Patients reported the following on clinical assessment: nasal obstruction (51 out of 59; 86 per cent), nasal discharge (30 out of 59; 51 per cent), hyposmia (15 out of 59; 25 per cent) and epistaxis (9 out of 59; 15 per cent).
Pre-operative CT and magnetic resonance imaging scans performed to evaluate the unilateral nasal polyp were conducted in 63 cases (82 per cent) and 8 cases (10 per cent), respectively.
Patients underwent the following operations: simple polypectomy, in 38 cases (49 per cent); and polypectomy with FESS, in 39 cases (51 per cent).
On histological assessment, 60 cases (78 per cent) were simple inflammatory nasal polyps; 4 (5 per cent) were other non-neoplastic lesions; and 13 (17 per cent) were neoplastic. Of the neoplasms, 11 (14.3 per cent) were benign and 2 (2.6 per cent) were malignant. The most common benign neoplasm was inverted papilloma (11.7 per cent). Table 1 shows the distribution of histological diagnoses. Table 2 shows the various sites of origin, as documented intra-operatively.
Table 1. Distribution of histological diagnoses
The two patients presenting with malignant pathology both had initially benign-appearing disease. The patient with an adenoid cystic carcinoma had presented with a unilateral nasal polyp that clinically appeared benign but was in an unusual location. The polyp appeared to be arising from the inferior turbinate and inferior meatus, with extension into the maxillary sinus. Pre-operative CT imaging of the paranasal sinuses revealed a suspicious mass centred on the left maxillary antrum, with bony erosion. Magnetic resonance imaging demonstrated tumour extension into the left maxillary sinus, left parapharyngeal space and skull base. The patient with a malignant melanoma presented because of persistent nasal obstruction and epistaxis, and had a polyp that appeared benign both clinically and radiologically.
Discussion
This study sought to determine the incidence of significant pathology in patients presenting with benign-appearing unilateral nasal polyps. A PubMed and Embase database search (conducted in February 2021) yielded 12 articles evaluating histopathological diagnosis in unilateral nasal polyps (Table 3).Reference Belli, Yildirim, Eroglu and Emre3–Reference Wooles, Bell and Adair14 Studies have mostly examined patients presenting with unilateral nasal masses (including polyps and other suspicious nasal masses) and reported on distributions of pathologies (Table 3).Reference Belli, Yildirim, Eroglu and Emre3–Reference Paz Silva, Pinto, Corey, Mhoon, Baroody and Naclerio9
Table 3. Studies evaluating histopathological results in patients with unilateral nasal polyps and masses
*Only 48 per cent of specimens sent for histology. †Reported 2.1 per cent with unexpected diagnosis. UNP = unilateral nasal polyp; FESS = functional endoscopic sinus surgery; NK = not known
Four studies evaluated histopathology in patients presenting with benign-appearing unilateral nasal polyps. The reported rates of benign neoplasm ranged from 0 to 15.9 per cent, and malignant neoplasms ranged from 0 to 6.3 per cent.Reference Romashko and Stankiewicz10–Reference Arslan, Hidir, Durmaz, Karslioglu, Tosun and Gerek13
Two studies from Turkey demonstrated comparable findings regarding rates of benign and malignant neoplasm in patients presenting with benign-appearing unilateral nasal polyps. A study of 54 patients by Arslan et al. found 5 cases (9.3 per cent) of benign neoplasm (5 inverted papilloma) and 2 cases (3.7 per cent) of malignant neoplasm (squamous cell carcinoma and chondrosarcoma).Reference Arslan, Hidir, Durmaz, Karslioglu, Tosun and Gerek13 Yaman et al. found that 5 of 32 patients (15.6 per cent) had benign neoplasm (2 inverted papilloma, 1 plasmacytoma, 1 schwannoma, 1 haemangioma), and 1 (3.1 per cent) had malignancy (esthesioneuroblastoma).Reference Yaman, Alkan, Yilmaz, Koc and Belada12
Tritt et al. evaluated pathological specimens in 44 patients who presented with unilateral nasal polyps in North America.Reference Tritt, McMains and Kountakis11 They found eight (18.2 per cent) benign neoplasms (seven inverted papillomas and one human papilloma virus polyp-like papilloma) and three (6.8 per cent) malignant lesions (two squamous cell carcinomas and one esthesioneuroblastoma). A second US study, by Romashko and Stankiewicz, found no significant pathologies in 13 patients presenting with unilateral nasal polyps, but this study was limited by a small sample size.Reference Romashko and Stankiewicz10
Our findings of benign (14.3 per cent) and malignant (2.6 per cent) neoplasms in benign-appearing unilateral nasal polyps fall within the range of previous reports from Europe and North America. Although malignancy is a relatively rare occurrence in patients with unilateral nasal polyps, benign neoplasms, and, in particular, inverted papillomas, are not uncommon. In general, patients with inverted papillomas require further endoscopic surgery to ensure complete clearance, for confirmation of no synchronous malignancy, and to minimise the risk of a metachronous malignancy occurring in the future.
• Our data support routine histological assessment for all unilateral nasal polyps, even if clinically benign-appearing
• Benign neoplasms represent around 15 per cent of all benign-appearing unilateral nasal polyps
• Malignant pathology is relatively rare in patients presenting with benign-appearing unilateral nasal polyps
• Malignancy must always be considered, and ideally ruled out, in patients with unilateral nasal polyps
• Patients can be informed that malignancy risk is relatively low (2.6 per cent)
• In elderly, unfit patients with minimal symptoms, initial conservative management may be reasonable
There are some limitations to this study. The quality of the medical record data on the clinical presentation of the nasal polyps was limited by the retrospective nature of the study.
To our knowledge, this study represents the largest investigation to date that specifically evaluates the histopathology of benign-appearing unilateral nasal polyps. Our findings further characterise the pathology of benign-appearing unilateral nasal polyps, and provide data to inform guidelines on the investigation and management of this condition.
In general, our experience suggests that histological findings should be obtained in cases of benign-appearing unilateral nasal polyps. It is important to note that a polyp which appears benign both clinically and radiologically may still represent a malignant pathology. In selected cases, a conservative approach may be appropriate, at least initially, if the following apply: the patient is not considered fit enough or not willing to undergo surgical intervention, and the polyp is asymptomatic, at a site typical of inflammatory polyps and with no significant features on imaging. Careful follow up may be required.
Conclusion
Our data support the routine histological assessment of unilateral nasal polyps, even if the polyp is considered to be non-neoplastic on clinical and radiological assessment. Malignancy is a rare occurrence (2.6 per cent in our population) in patients with benign-appearing unilateral nasal polyps, but the possibility of malignancy should always be considered. Benign neoplasms (14.3 per cent), and in particular inverted papillomas, were not an uncommon finding. The majority of patients with tumours underwent further FESS. In carefully selected cases, conservative management may be an appropriate strategy, at least initially.
Competing interests
None declared
