The paranasal sinuses consist of four paired air-containing cavities—maxillary, frontal, ethmoidal, and sphenoidal—lined by respiratory mucosa and communicating with the nasal cavity through narrow ostia. These sinuses play an important role in humidification and filtration of inspired air, voice resonance, and reduction of skull weight. Physiological drainage through coordinated mucociliary clearance is essential for maintaining sinus sterility and functional integrity. Even minor disturbances in ventilation or ostial patency may predispose the mucosa to inflammation and infection.¹ Anatomical variations within the sinonasal region are common and frequently identified on computed tomography (CT) imaging. While many of these variations are incidental findings, certain structural deviations may influence sinus aeration and drainage patterns. Deviated nasal septum (DNS), concha bullosa (pneumatized middle turbinate), agger nasi cells, Haller cells, Onodi cells, and paradoxical middle turbinate are among the most frequently reported variations.² These alterations can reduce the caliber of the ostiomeatal complex, the key drainage pathway for the maxillary, frontal, and anterior ethmoid sinuses.³ The ostiomeatal complex is considered a critical anatomical region in the development of chronic and recurrent sinus disease. Obstruction within this area can result in stagnation of secretions, mucosal edema, and impaired oxygenation of sinus cavities, thereby promoting microbial growth.⁴ The principles of functional endoscopic sinus surgery (FESS) are largely based on restoring normal ventilation and mucociliary function by correcting these anatomical impediments.⁵ Fungal sinusitis represents a heterogeneous group of disorders ranging from non-invasive forms such as fungal ball and allergic fungal sinusitis to invasive variants. The condition is particularly prevalent in regions with warm and humid climates.⁶ In the Indian subcontinent, fungal pathogens—especially Aspergillus species—are commonly implicated in chronic and recurrent sinonasal infections.⁷ Environmental exposure to fungal spores, coupled with impaired sinus drainage, may facilitate colonization within poorly ventilated sinus cavities.⁸ Radiological imaging, particularly CT scanning of the paranasal sinuses, remains the gold standard for evaluating sinonasal anatomy and identifying variations that may predispose to disease.⁹ Concurrent microbiological assessment through potassium hydroxide (KOH) mount, fungal culture on Sabouraud dextrose agar, and species identification techniques provides definitive confirmation of fungal etiology.¹⁰ An integrated anatomical and microbiological evaluation allows for better understanding of the structural factors contributing to recurrent fungal sinusitis. Although numerous studies have described the prevalence of sinonasal anatomical variations and their association with chronic rhinosinusitis, limited literature specifically examines their correlation with recurrent fungal sinusitis. Establishing this association is clinically significant, as recognition of high-risk anatomical patterns may guide early intervention strategies and improve therapeutic outcomes. Therefore, the present study aims to analyze the anatomical variations of the paranasal sinuses and determine their association with recurrent fungal sinusitis using combined radiological and microbiological methods.

Study Design The present study was designed as a hospital-based cross-sectional analytical study conducted to evaluate the association between anatomical variations of the paranasal sinuses and recurrent fungal sinusitis through radiological and microbiological assessment. Study Setting The study was carried out in the Departments of Anatomy, Microbiology, and Otorhinolaryngology (ENT) at a tertiary care teaching hospital. Radiological evaluation was performed in the Department of Radiodiagnosis, and microbiological analysis was conducted in the Central Microbiology Laboratory. Study Duration The study was conducted over a period of 12 months. Study Population A total of 120 patients clinically suspected of recurrent fungal sinusitis and referred for CT scan of paranasal sinuses were included in the study. Sample Size The sample size was calculated based on the expected prevalence of anatomical variations in patients with chronic rhinosinusitis, reported to range between 50% and 65% in previous radiological studies.¹,² Assuming a prevalence (p) of 55%, with 95% confidence interval and 9% absolute precision, the minimum required sample size was calculated using the formula: n=(Z^2×p×q)/d^2 Where: Z=1.96 (for 95% confidence level) p= expected prevalence (0.55) q=1 – p d = allowable error (0.09) The calculated sample size was 118, which was rounded to 120 participants. Inclusion Criteria Patients aged 18–65 years History of recurrent sinusitis (≥3 episodes per year or persistent symptoms >12 weeks despite treatment) Radiological suspicion of fungal sinusitis Patients willing to provide informed consent Exclusion Criteria Sinonasal malignancy History of facial trauma or previous sinus surgery Congenital craniofacial anomalies Patients on long-term antifungal therapy Severely immunocompromised patients (except controlled diabetes mellitus) Ethical Considerations The study was approved by the Institutional Ethics Committee. Written informed consent was obtained from all participants prior to inclusion. Radiological Evaluation All patients underwent Computed Tomography (CT) scan of paranasal sinuses using a multi-detector CT scanner. CT Protocol Coronal, axial, and sagittal sections Slice thickness: 3–5 mm Bone window and soft tissue window settings Images analyzed by an experienced radiologist Anatomical Variations Assessed The following anatomical variations were systematically evaluated: Deviated nasal septum (DNS) Septal spur Concha bullosa (unilateral/bilateral) Paradoxical middle turbinate Agger nasi cells Haller cells (infraorbital ethmoid cells) Onodi cells (sphenoethmoidal cells) Hypertrophy of turbinates Ostiomeatal complex obstruction Each variation was documented as present or absent. Degree of sinus involvement (maxillary, ethmoid, frontal, sphenoid) was recorded. Radiological findings suggestive of fungal sinusitis included: Hyperdense sinus opacification Heterogeneous density with calcifications Sinus expansion without bony destruction (non-invasive) Microbiological Evaluation Samples were obtained from sinus aspirates or intraoperative specimens under aseptic precautions. Direct Microscopy 10% Potassium hydroxide (KOH) mount preparation Observation for fungal hyphae (septate/non-septate) Lactophenol cotton blue (LPCB) staining for morphological identification Fungal Culture Specimens were inoculated onto: Sabouraud Dextrose Agar (SDA) with chloramphenicol SDA with cycloheximide Incubation conditions: Temperature: 25°C and 37°C Duration: up to 4 weeks Growth characteristics such as colony morphology, pigmentation, and microscopic features were recorded. Identification of Fungal Isolates Fungal species were identified based on: Macroscopic colony morphology Microscopic appearance on LPCB mount Arrangement of conidiophores and spores Commonly expected isolates: Aspergillus fumigatus Aspergillus flavus Mucor species Candida species Statistical Analysis Data were entered in Microsoft Excel and analyzed using SPSS version 19.0. Categorical variables were expressed as frequency and percentage. Continuous variables were expressed as mean ± standard deviation (SD). Chi-square (χ²) test was applied to determine the association between anatomical variations and occurrence of recurrent fungal sinusitis. Odds Ratio (OR) with 95% Confidence Interval (CI) was calculated to measure the strength of association between specific anatomical variations and fungal sinusitis. A p-value of less than 0.05 was considered statistically significant

A total of 120 patients clinically diagnosed with recurrent fungal sinusitis were included in the study. All patients underwent radiological and microbiological evaluation. The majority of patients belonged to the 31–45 years age group (45%). Male patients (60%) outnumbered female patients (40%), with a male-to-female ratio of 1.5:1 as shown in table 1. Table 1: Age and Gender Distribution of Study Participants (n = 120) Variable Number (n) Percentage (%) Age Group (years) 18–30 32 26.6 31–45 54 45.0 46–65 34 28.3 Gender Male 72 60.0 Female 48 40.0 Deviated nasal septum (65%) was the most common anatomical variation observed, followed by concha bullosa (48%) and agger nasi cells (40%). Onodi cells were the least common (12%) as shown in table 2. Table 2: Distribution of Anatomical Variations on CT Scan (n = 120) Anatomical Variation Number (n) Percentage (%) Deviated Nasal Septum 78 65.0 Concha Bullosa 58 48.3 Agger Nasi Cells 48 40.0 Paradoxical Middle Turbinate 26 21.6 Haller Cells 22 18.3 Onodi Cells 15 12.5 Septal Spur 30 25.0 Maxillary sinus involvement was the most frequent (72%), followed by ethmoid sinus (55%). Sphenoid sinus involvement was observed in 20% of cases as shown in table 3. Table 3: Distribution of Sinus Involvement (n = 120) Sinus Involved Number (n) Percentage (%) Maxillary 86 71.6 Ethmoid 66 55.0 Frontal 42 35.0 Sphenoid 24 20.0 Aspergillus species accounted for 70% of isolates, with Aspergillus fumigatus being the predominant species (50%). Culture positivity rate was 88% as shown in table 4. Table 4: Distribution of Fungal Isolates (n = 120) Fungal Isolate Number (n) Percentage (%) Aspergillus fumigatus 60 50.0 Aspergillus flavus 24 20.0 Mucor species 18 15.0 Candida species 12 10.0 Others 6 5.0 A statistically significant association was observed between deviated nasal septum and maxillary fungal sinusitis (p = 0.003). Concha bullosa also showed significant association with ostiomeatal complex obstruction (p = 0.001) as shown in table 5 Table 5: Association Between Deviated Nasal Septum and Maxillary Sinus Involvement DNS Maxillary Involvement Present Absent Total p-value Present (n=78) 66 12 78 0.003* Absent (n=42) 20 22 42 *Statistically significant (p < 0.05) OMC obstruction was significantly higher in patients with concha bullosa (86.2%) compared to those without (38.7%) (p = 0.001), indicating a strong association as shown in table 6 Table 6: Association Between Concha Bullosa and Ostiomeatal Complex Obstruction Concha Bullosa OMC Obstruction Present Absent Total p-value Present (n=58) 50 8 58 0.001* Absent (n=62) 24 38 62 *Statistically significant (p < 0.05)

The present study evaluated the relationship between anatomical variations of the paranasal sinuses and recurrent fungal sinusitis using combined radiological and microbiological assessment. Our findings demonstrate a high prevalence of structural variations, particularly deviated nasal septum and concha bullosa, with significant association to ostiomeatal complex obstruction and fungal involvement. Deviated nasal septum (65%) was the most frequently observed anatomical variation in our study. Similar prevalence ranging from 60–70% has been reported in patients with chronic rhinosinusitis.¹² Septal deviation alters nasal airflow dynamics and may cause narrowing of the middle meatus, resulting in impaired sinus drainage. Chronic mucosal edema secondary to obstruction creates a favorable microenvironment for fungal colonization.¹³ Concha bullosa was identified in 48% of patients and showed a statistically significant association with ostiomeatal complex obstruction (p = 0.001). Pneumatization of the middle turbinate may mechanically compress the infundibulum, thereby compromising ventilation of the maxillary and anterior ethmoid sinuses.¹⁴ Previous radiological studies have similarly demonstrated that enlarged concha bullosa is a significant predisposing factor for sinus disease.¹⁵ Agger nasi cells (40%) and Haller cells (18%) were also commonly observed. These anterior ethmoidal air cells can encroach upon the frontal recess and maxillary ostium, respectively, leading to obstruction.¹⁶ Studies have shown that infraorbital ethmoid (Haller) cells are significantly associated with maxillary sinusitis due to narrowing of the ostium.¹⁷ Maxillary sinus involvement (72%) was the most common pattern in our series. The anatomical position of the maxillary sinus ostium—located superiorly on the medial wall—predisposes it to secretion retention when drainage is compromised.¹⁸ Fungal colonization in poorly ventilated maxillary sinuses has been widely documented, especially in tropical climates.¹⁹ Microbiological analysis revealed that Aspergillus species accounted for 70% of isolates, with Aspergillus fumigatus being predominant. This finding aligns with earlier Indian studies reporting Aspergillus as the most frequent etiological agent in non-invasive fungal sinusitis.²⁰ The ubiquity of Aspergillus spores in the environment, coupled with impaired sinus clearance, contributes to recurrent infection.²¹ The statistically significant association between anatomical variations affecting the ostiomeatal complex and fungal sinusitis observed in this study supports the theory that structural factors play a critical role in disease persistence. Obstruction results in reduced oxygen tension and accumulation of secretions, conditions conducive to fungal growth.²² This reinforces the importance of CT-based anatomical mapping prior to surgical intervention. Functional endoscopic sinus surgery (FESS), aimed at correcting anatomical blockages and restoring sinus ventilation, has shown favorable outcomes in preventing recurrence.²³ Identification of high-risk anatomical patterns preoperatively may therefore improve treatment planning and long-term prognosis. Although systemic risk factors such as diabetes and immunosuppression are recognized contributors, our findings emphasize that local anatomical factors independently influence recurrence. Early radiological detection of obstructive variations may allow timely intervention and reduce morbidity. The integration of radiological anatomy with microbiological confirmation in this study provides a comprehensive understanding of the structural–infective interplay in recurrent fungal sinusitis. Further multicentric studies with larger sample sizes may strengthen the observed associations.

The present study highlights that anatomical variations of the paranasal sinuses, particularly deviated nasal septum and concha bullosa, are significantly associated with recurrent fungal sinusitis. These variations contribute to ostiomeatal complex obstruction, impairing sinus ventilation and drainage, thereby promoting fungal colonization. Maxillary sinus involvement was most common, with Aspergillus species as the predominant pathogen. Combined radiological evaluation and microbiological confirmation are essential for accurate diagnosis and effective management. Early identification and correction of obstructive anatomical variations may help reduce recurrence and improve patient outcomes.

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