Histopathological study of lesions of nasal cavity and paranasal sinuses

Introduction: The nasal cavity and paranasal sinuses are exposed to many environmental pollutants and pathogens. Exposure to such influences can lead to a variety of lesions primarily affecting the sinonasal tract. The aim of this study was to find out the incidence, age and sex distribution and to enlist the different types of lesions of the nasal cavity and paranasal sinuses. Materials and Methods: A study of 122 cases was conducted over a 2 year period. Both retrospective and prospective cases were included in the study. All relevant clinical details, tissue sections with H&E, special stains and IHC stains were done whenever necessary. Result: Out of 122 cases, 98 non-neoplastic cases and 24 neoplastic cases were diagnosed. Maximum n on-neoplastic cases were detected in the third and fourth decade. Benign lesions were commonly noted in fourth and seventh decade. Malignant lesions of sinonasal tract commonly afflicted patients of 61 to 70 years of age. Non-neoplastic and benign lesions showed male predominance. Female preponderance was noted in malignant lesions of sinonasal tract. Among non-ne oplastic lesions, sinonasal polyp (84 cases) was most prevalent. Maximum proportion of benign lesions were diagnosed as hemangioma (6 cases) and sinonasal papilloma (5 cases). Among malignant neoplastic lesions, 4 cases were of squamous cell carcinoma and 3 cases were of malignant melanoma. Conclusion: A variety of lesions with overlapping clinical features can affect the sinonasal tract. Histopathology remains the gold standard for establishing the diagnosis in such cases. © 2020 Published by Innovative Publication. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by/4.0/)


Introduction
'Sinonasal tract' is a collective term used for nasal cavity and paranasal sinuses. 1 The main functions of the sinonasal tract are filtering and humidifying inhaled air. The nasal cavity also has specific olfactory receptors for airborne odorant molecules. The paranasal sinuses additionally have the functions of acting as resonating chambers during speech and reducing the relative weight of the skull. 2 These functions lead to exposure of various allergens, pathogens, chemical and physical irritants and other environmental influences. As a result of these multifaceted exposures, various inflammatory conditions, infections and neoplasms can occur in the sinonasal tract. 3 Prevalence of sinonasal masses in the general population is 1 to 4%. 4 A careful clinical workup including symptomatology, radiological investigations and endoscopy helps to determine a differential diagnosis but histopathology provides the final diagnosis. 5 Thus histopathological examination is essential for timely diagnosis and intervention. 6

Material and Methods
Th is study was a descriptive cross-sectional study and was carried out in the Pathology department of a tertiary care hospital. Institute Ethics Committee Clearance (IECC) was obtained before start of the study.
The study took 2 years for completion and 122 cases from September 2011 to August 2018 were studied. Cases from September 2011 to August 2016 were part of the Of the total 122 cases included in this study, the nonneoplastic cases (98 cases) outnumbered the neoplastic cases (24 cases). Cases diagnosed as benign lesions (13 cases, 10.66%) were marginally higher than those diagnosed as malignant (11 cases, 9.01%).

Discussion
In the present study, age of presentation showed a wide range from 2 to 90 years. Maximum cases were noted in the fourth decade (28 cases, 22.95%) followed by the third decade (27 cases, 22.13%). Raj et al found maximum cases in third decade (32.79%) followed by fourth decade (21.31%). 8 In the study conducted by Mane et al, the most (H&E, 400X) Inset: GMS stain highlights the thin, branching hyphae common age group was 21-30 years (35 cases, 27.78%) followed by 31-40 years (31 cases, 24.60%). 9 Male to female ratio of 1.39:1 was calculated in this study. Similar findings of male preponderance were observed in studies conducted by Tondon et al, 10 Khan et al 11 and Kulkarni et al. 6 We observed higher frequency of non-neoplastic lesions (80.33%) in comparison with neoplastic lesions (19.67%). Our findings are in concordance with Khan et al, 11 Kulkarni et al 6 and Mane et al. 9 However Dasgupta et al 12 recorded

Sinonasal polyps
Peak incidence of sinonasal polyps was noted in the third decade. Similar findings were observed by Khan et al 11 and Kulkarni et al 6 who reported a peak incidence in second and third decade of life. Male predominance was observed and this was in compliance with the studies by Dasgupta et al 12 and Khan et al. 11 Microscopically, the epithelial lining   is ciliated pseudostratified columnar, with stromal infiltrate comprising of eosinophils, lymphocytes and neutrophils. (Figure 1)

Fungal rhinosinusitis
According to this study, the mean age of presentation of patients diagnosed with fungal rhinosinusitis was 62.4 years wit h female predominance (M:F ratio 1:1.5). Mane et al 9 reported the mean age of presentation of fungal rhinosinusitis was 50.7 years with male preponderance (2:1). This suggests that fungal rhinosinusitis mainly affects the elderly. On microscopy, the fungal hyphae were thin and branching at acute angles. (Figure 2)

Neoplastic lesions of sinonasal tract
In the present study, benign neoplastic lesions (54.17%) marginally outnumbered the malignant neoplastic lesions (45.83%). Similar findings were noted in the study by Khan et al. 11 But Tondon et al 10 and Mane et al 9 reported a higher proportion of benign neoplastic lesions (73.53% and 71.43% respectively) compared to malignant lesions (26.47% and 28.57% respectively).

Benign neoplastic lesions of sinonasal tract
Maximum benign neoplastic lesions of sinonasal tract in our study were seen in the 31 to 40 years and 61 to 70 years age group. Mane et al 9 reported similar findings where benign tumours were reported commonly in fourth decade. Male preponderance was reported in benign neoplastic lesions and this was corroborated by Kulkarni et al, 6 Raj et al 8

Hemangioma
It was noted that hemangioma could occur in any age group but was most commonly noted in the fourth decade. This finding was in accordance with Dasgupta et al 12

Squamous cell carcinoma
The age range of patients with squamous cell carcinoma observed was 18 to 65 years and the mean age of presentation calculated was 39.5 years. Dasgupta et al 12 noted the mean age of presentation as 52.3 years for patients suffering from sinonasal squamous cell carcinoma whereas Khan et al 11 reported peak incidence of squamous cell carcinoma in the sixth and seventh decade of life. We found that only females were affected by squamous cell carcinoma. However, Dasgupta et al 12 and Khan et al 11 noted a male predominance (2:1). This variation can be attributed to the small sample size (4 cases) in our study. On microscopy, infiltrating nests of squamous epithelial cells were noted. The epithelial cells were highly pleomorphic with hyperchromatic nuclei, nuclear atypia and abnormal mitotic figures. Keratin pearls were observed.

Malignant melanoma
Peak incidence of malignant melanoma was in the seventh decade. Khan et al 11 noted maximum cases in the fourth decade.
In the current series, all malignant melanoma cases were females.
Khan et al 11 noted equal sex distribution. Microscopic examination revealed atypia of melanocytes with prominent nucleoli and mitotic activity. On immunohistochemistry, neoplastic cells showed reactivity for HMB-45 and S-100. (Figure 6)

Conclusion
To conclude, various types of lesions affect the sinonasal tract. These lesions can affect any age group. Irrespective of their etiology, whether non-neoplastic or neoplastic, the lesions can present with similar clinical features. Radiological studies and other investigations can help provide a differential diagnosis, but the final diagnosis can only be given on histopathological examination. Definite diagnosis is essential for further management and to determine the prognosis of the patient. Therefore histopathology plays an intergral role and remains the gold standard for establishing the diagnosis of sinonasal tract lesions.

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Conflict of interest
None.