Evaluation of Anatomical Variations of the Maxillary Sinus in Patients With and Without Mucous Retention Cyst

Abstract

Objectives: Mucous retention cyst (MRC) is a benign and self-limited lesion that can be caused by many risk factors, including anatomical variations of the sinonasal region. This study aims to investigate the relationship between anatomical variations and the presence of MRC. Materials and Methods: In total, 2109 sinonasal cone beam computed tomography images were evaluated for the presence of MRC, and the sinonasal anatomical regions such as the osteomeatal complex (OMC), infundibulum length, ostium height, the diameter of the ostium, the presence of accessory ostium, concha bullosa, and mucosal thickening of the maxillary sinuses. Shapiro-Wilk normality test, independent sample t-test, and chi-square test were used for statistical analysis, and P < .05 was considered significant. Results: The prevalence of MRC was 119 (5.6%) cases. The average diameter of the ostium in cases with and without MRC was 0.49 ± 0.41 mm and 0.99 ± 0.76 mm, respectively, which showed a significant inverse relationship(P < .001). A significant relationship was found between the septum deviation, the ostium height, the concha bullosa, and the accessory ostium with the presence of MRC (P < .001). Conclusions: Sinonasal anatomical variations such as ostium diameter, ostium height, septal deviation, the presence of accessory ostium, and concha bullosa can cause MRC development, and considering that surgery may be necessary in some cases; this could be of great importance to clinicians and surgeons for treatment and prevention of development or recurrence of these pseudocysts in patients.

Keywords

cone beam computed tomography anatomic variation maxillary sinus nasal septum turbinates

Introduction

A mucous retention cyst (MRC) is a benign and self-limiting lesion that results from the mucosal outflow of the sinus membrane due to ductal obstruction. This retention cyst has a non-odontogenic origin and has been found in both edentulous and non-edentulous patients.¹

The prevalence of MRC, in the general population, ranges from 3.2% to 35.6%.² Many etiological factors have been declared to cause MRC, including allergies, sinonasal inflammation due to anatomical variations in the osteomeatal complex (OMC) and sinuses, trauma, and periapical and periodontal infections.

Most of these lesions are asymptomatic, and 17.6% to 38.9% regress spontaneously.² However, some cysts may cause symptoms such as headache, facial pain, peri-orbital pain, frequent paranasal sinus infections, or nasal obstruction; so surgical treatment may be necessary.^2,3 In imaging features, MRC can be found as a well-defined round or dome-shaped radio-opaque lesion with no cortical border in the maxillary sinus.¹

Panoramic and cone beam computed tomography (CBCT) images can be helpful in diagnosing sinus lesions such as MRC, but for a detailed evaluation of the maxillofacial region, high-resolution CBCT images are more effective than panoramic. CBCT is an important tool for evaluating and planning treatment, based on changes in the maxillary sinus.⁴

Many anatomical variations of the sinonasal region can cause an accumulation of seromucous materials and lead to an increased risk of MRC development. Some MRCs may enlarge gradually and develop an antrochoanal cyst.² A better understanding of etiological factors can be important in the prevention of future complications. So, the main purpose of this study is to investigate the relationship between anatomical variations of the maxillary sinus and the presence of MRC.

Materials and Methods

As a result, 2109 scans of the sinonasal region of 1231 patients were selected from the database of the faculty of dentistry and private oral and maxillofacial radiology clinics in Babol City between 2015 and 2023. The sample size was calculated according to the formula [n = Z²P (1 − P)/d²], considering (Z) = 1.96 for the 95% confidence level, (P) = .25 for the prevalence of MRC, and a margin of error (d) = 0.02. The sample size was estimated to be 1800 but for more accuracy, the number of samples was increased by 15%, and finally, 2109 scans of patients were included in this research.

Patients in mixed dentition, with nasal masses, anatomical defects due to previous surgeries, and images with poor quality were excluded. Local ethics committee approval was obtained (approval NO: IR.MUBABOL.REC.1401.081).

All CBCT scans, which were taken with 85 kvp, 10 mA, 30 seconds, and 200 μ voxel size, were reviewed by an oral-maxillofacial radiologist in a semi-dark room using a 23.8-inch LCD monitor with a color depth of 24 bits (Dell, Beijing, China). OnDemand3D Dental (Cybermed Inc., Seoul, Korea) and NNT Viewer (New Tome, Verona, Italy) software were used to visualize images in the coronal view (thickness = 0.5 mm and interval = 0.15 mm) and have been evaluated for the presence of MRC. The diagnostic criteria for MRC are as follows: A uniform, dense, spherical, or dome-shaped lesion with no cortical borders and no bone destruction that originates from the walls or floor of the maxillary sinus (Figure 1). Then the cases were reviewed for the anatomical variations of the sinonasal region including OMC, length of infundibulum, the distance between ostium and maxillary sinus floor, the diameter of ostium in the narrowest area, the presence of accessory ostium, abnormality of middle turbinate (concha bullosa), and maxillary sinus abnormalities (such as mucosal thickening) (Figures 2 and 3). In the end, the relationship between the presence of MRC and all the anatomical variations mentioned above was analyzed. To determine intra-observer reliability, 10% of the samples were randomly selected and after a 2-week interval, the images were re-evaluated, and the intra-observer correlation coefficient (ICC) was calculated. Data were analyzed using SPSS version 22 (SPSS Inc., IL, USA). The normality distribution of continuous data was confirmed by the Shapiro-Wilk test and the parametrical test of independent sample T-test was used. To analyze the categorical data, the chi-square test was used. P < .05 was considered significant.

Results

Among the 1231 patients, 466 (38%) were men and 765 (62%) were women, with a mean age of 35.1 ± 13.1 years (range: 13-83). Out of 2109 sinus scans, 1088 (51.6%) were right side and 1021 (48.4%) left side. The prevalence of MRC in this study was 119 (5.6%) cases (Table 1).

Table 1.

Demographic Description of Cases With and Without MRC.

Gender	Mucous retention cyst		Total	P value
Gender	No	Yes	Total	P value
Male N (%)	714 (91.5)	66 (8.5)	780 (37)	<.001
Female N (%)	1276 (96)	53 (4)	1329 (63)
Total N (%)	1990 (94.4)	119 (5.6)	2109 (100)

The average diameter of ostium in all 2109 cases for men and women was (0.78 ± 0.77 mm) and (1.07 ± 0.72 mm), respectively (P < .001). The average diameter of ostium in cases with and without MRC was 0.49 ± 0.41 mm and 0.99 ± 0.76 mm, respectively, which showed a significant inverse relationship (P < .001) (Table 2). There was no significant relationship between the length of the infundibulum and MRC (P = .237) (Table 2).

Abbreviation: MRC, mucous retention cyst.

The average distance between the ostium and the floor of the maxillary sinus in cases with and without MRC was 33.63 ± 4.70 mm and 30.26 ± 4.91 mm, respectively, which was statistically significant (P < .001) (Table 2).

Table 2.

Mean Values (±SD) of Ostium Width, Infundibulum Length, and Ostium Height in Cases With and Without MRC.

MRC	N	Mean	Std. deviation	Std. error mean	P value
Ostium width
Present	119	0.492	0.4165	0.0382	<.001
Absent	1990	0.997	0.7651	0.0172	<.001
Infundibulum length
Present	82	10.853	3.0226	0.3338	.237
Absent	1455	10.464	2.8872	0.0757	.237
Distance of ostium to maxillary sinus floor
Present	82	33.63	4.720	0.521	<.001
Absent	1455	30.26	4.961	0.130	<.001

Abbreviation: MRC, mucous retention cyst.

Out of 119 scans with MRC, 97(81.5%) scans presented with septal deviation (P < .01), 15 (12.6%) scans presented with accessory ostium (P < .01), and 22 (18.5%) scans with concha bullosa (P < .01), which were statistically significant (Table 3).

Table 3.

Frequency of Septum Deviation, Concha Bullosa, Accessory Ostium, Mucosal Thickening, and OMC Obstruction in Cases With and Without MRC.

	MRC N, (%)		Total (%)	P value
	Absent (%)	Present (%)	Total (%)	P value
Septum deviation
No	775 (38.9)	22 (18.5 )	797 (37.8)	<.001
Yes	1215 (61.1)	97 (81.5)	1329 (62.2)	<.001
Concha bullosa
No	1835 (92.2)	97 (81.5 )	1932 (91.6 )	<.001
Yes	155 (7.8)	22 (18.5)	177 (8.4)	<.001
Accessory ostium
No	1926 (96.8)	104 (87.4)	2030 (96.3)	<.001
Yes	64 (3.2)	15 (12.6)	79 (3.7)	<.001
Mucosal thickening
No	1153 (57.9)	82 (68.9)	1235 (58.6)	.018
Yes	837 (42.1)	37 (31.1)	874 (41.4)	.018
OMC obstruction
No	1455 (73.1)	82 (68.9)	1537 (72.9)	.316
Yes	535 (26.9)	37 (31.1)	572 (27.1)	.316

Abbreviations: MRC, mucous retention cyst; OMC, osteomeatal complex.

Among the maxillary sinuses with MRC, 37 (31.1%) encountered OMC obstruction (P = .316) (Table 3).

Of the 119 scans with MRC, 37 (31.1%) had increased mucosal thickening, which showed a significant inverse relationship (P = .018) (Table 3).

The prevalence of MRC was higher in November (18.5%) and October (13.5%), respectively. (P = .878) (Figure 4).

After 2 weeks, 210 (10%) cases were randomly evaluated; and the ICC was calculated as 0.99.

Discussion

In this study, the prevalence of MRC was 5.6% which was similar to other studies in the literature.^5-7 MRC incidence was significantly higher in men than women which was consistent with Niknami et al.⁸ and Rastegar et al.,⁹ but Lacin et al.⁶ and Yeung et al.¹⁰ showed no significant difference.

The diameter of the ostium in the whole population of this study was significantly lower in men than women which is in agreement with Peters et al.¹¹ in Malaysians, but Souza et al.¹² showed no significant difference in Indian patients. Also, the diameter of the ostium was significantly lower in cases with MRC than others. However, Freitas et al.¹³ in 328 CBCT scans of Brazilians reported no significant relationship between ostium diameter and sinus changes as mucosal thickening, antral pseudocyst, and other conditions. Differences in the results could be due to the sample size, ethnic background, and previous allergic reactions.

Considering the results that the diameter of the ostium was generally lower in men than women in this community and the higher prevalence of MRC in men than women, it can be concluded that a smaller ostium diameter in men can increase the risk of MRC.

Regarding the ostium height, studies are limited. Akay et al.¹⁴ and de Carvalho et al.¹⁵ showed that an increase in ostium height can cause disturbances in the drainage of seromucosal materials and lead to an increased risk of MRC in antrum, that is, in line with our results.

Some previous studies reported that septal deviation can play a major role in the presence of MRC and our results are compatible with them,^16-19 while some others showed no correlation between septal deviation and sinus diseases.^20,21

In terms of accessory ostium, the results are controversial. Yenigun et al.²² declared that the presence of accessory ostium can increase the risk of MRC threefold, which is in accordance with our results, while another study conducted by Serindere et al.²³ showed that accessory ostium can decrease the incidence of MRC by 50%. However, some other studies showed no significant relationship in this respect.^24-26 This discrepancy between studies can be attributed to the differences in sample size, ethnic groups, and measurement techniques.

According to our results, concha bullosa can increase the risk of MRC development. To the best of our knowledge, no previous study has investigated the relationship between concha bullosa and MRC development, and only evaluation of other sinus diseases was reported in the literature. Some studies showed a significant correlation between concha bullosa and sinus diseases such as rhinosinusitis,^27,28 while others showed no correlation.^20,21,29,30

According to our study, the length of the infundibulum is not a predisposing factor for MRC development, which is in accordance with the study of de Carvalho et al.¹⁵ de Carvalho et al. declared that the length of the infundibulum is longer in patients with antral pseudocyst and shorter in patients with complete sinus opacification, but it was not a deterministic factor in this respect, and this could be due to previous obstruction of drainage system or in cases with antral pseudocyst; intrinsic structures of the caliciform cells in addition to drainage system obstruction can be effective. Also in another study, by Paşaoğlu et al.³¹ no significant correlation between infundibulum length and other sinus diseases like sinusitis was reported. However, Akay et al.¹⁴ and Yousefi et al.³² showed that the infundibulum was significantly shorter in cases with sinus pathoses.

Previous studies showed no correlation between OMC obstruction and MRC,^33-35 that our results are in line with them, while Arslan et al.⁴ showed a significant correlation in this respect. Bhattacharyya³³ declared that it is possible that OMC obstruction is an initial condition for MRC development; but while the MRC persists, the OMC may become patent, and only a longitudinal study can investigate this hypothesis.

The highest incidence of MRC was in November (18.5%) and October (13.4%), respectively, but it was not statistically significant, which is in line with the results of Rodrigues et al.³⁶ and Jafari-Pozve et al.³⁷ However, Rastegar’s⁹ study showed that the highest incidence of MRC was in spring (38.8%) and summer (18.8%), which was significant.

Conclusions

Considering that many anatomical variations can cause MRC, it is very important for clinicians to evaluate sinonasal anatomical variations such as ostium diameter, ostium height, septal deviation, the presence or absence of accessory ostium, and concha bullosa for better management of complications and treatment of patients. Surgical treatment of anatomic variations such as septum deviation and other conditions can help patients suffering from these cysts.

It is recommended to conduct more studies on other anatomical variations and their concurrence with each other and their effect on MRC development.

Footnotes

Authors’ Contributions

Sina Haghanifar designed and supervised the experiment, and critically revised the manuscript; Fateme Aghaee carried out the experiment; Fateme Aghaee wrote the manuscript; Ehsan Moudi-Nazmehr Vahdani provided the cases; and Ali Bijani did statistical analysis.

Consent to Participate

Not applicable.

Consent for Publication

Not applicable.

Data Availability

Not applicable.

Declaration of Conflicting Interests

The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The author(s) received no financial support for the research, authorship, and/or publication of this article.

Ethics Approval

Approval was obtained from the Ethics Committee of our institution. (Approval NO: IR.MUBABOL.REC.1401.081).

ORCID iD

Fateme Aghaee

References

Mallya

Lam

. White and Pharoah’s Oral Radiology. 8th ed. Elsevier; 2018

Moon

Kim

Han

Shin

Rhee

Lee

. Mucosal cysts in the paranasal sinuses: long-term follow-up and clinical implications. Am J Rhinol Allergy. 2011;25:98-102. doi:10.2500/ajra.2011.25.3567

Bal

Berkiten

Uyanık

. Mucous retention cysts of the paranasal sinuses. Hippokratia. 2014;18(4):379.

Arslan

İB

Uluyol

Demirhan

Kozcu

Pekçevik

Çukurova

. Paranasal sinus anatomic variations accompanying maxillary sinus retention cysts: a radiological analysis. Turk Arch Otorhinolaryngol. 2017;55(4):162-165. doi:10.5152/tao.2017.2759

Moon

Lee

Kim

, et al. Characteristics and risk factors of mucosal cysts in the paranasal sinuses. Rhinology. 2011;49(3):309-314. doi:10.4193/Rhino10.148

Lacin

Tatar

. Evaluation of the frequency of mucous retention cysts in the maxillary sinus in a Turkish population using cone-beam computed tomography. Makara J Health Res. 2019;23(2):68–71. doi:10.7454/msk.v23i2.10711

Marçal Vieira

de Morais

de Musis

, et al. Frequency of maxillary sinus mucous retention cysts in a central Brazilian population. J Dent (Shiraz). 2015;16(3):169-174.

Niknami

Mirmohammadi

Pezeshki

. Evaluation of the prevalence of mucous retention pseudocyst and its correlation with the associated risk factors using panoramic radiography and cone-beam computed tomography. J Dent (Tehran). 2018;15(2):123-129.

Rastegar

Osmani

. Evaluation of mucous retention cyst prevalence on digital panoramic radiographs in the local population of Iran. Radiol Res Pract. 2022;2022:8650027. doi:10.1155/2022/8650027

10.

Yeung

AWK

Tanaka

Khong

von Arx

Bornstein

. Frequency, location, and association with dental pathology of mucous retention cysts in the maxillary sinus. A radiographic study using cone beam computed tomography (CBCT). Clin Oral Investig. 2018;22(3):1175-1183. doi:10.1007/s00784-017-2206-z

11.

Peter

Nambiar

Krishnan

AL-Namnam

. The location and diameter of the primary maxillary sinus ostium: a cone-beam computed tomography study in Malaysians. J Int Dent Med Res. 2020;13(4):1365-1369. doi:10.14302/issn.2768-0207.jbr-20-3194

12.

Souza

Rajagopal

Ankolekar

Souza

Kotian

. Anatomy of maxillary sinus and its ostium: a radiological study using computed tomography. CHRISMED J Health Res. 2016;3(1):37. doi:10.4103/2348-3334.172397

13.

Freitas

GB de

Siquiera

França

AJB

, et al. Investigation of the relationship between the sinusal ostium diameter and changes in the maxillary sinus: a cone beam computerized tomography study. Res, Soc Develop. 2020;9(7):e957975103. doi:10.33448/rsd-v9i7.5103.

14.

Akay

Yaman

Karadağ

Güngör

. Evaluation of the relationship of dimensions of maxillary sinus drainage system with anatomical variations and sinusopathy: cone-beam computed tomography findings. Med Princ Pract. 2020;29(4):354-363. doi:10.1159/000504963

15.

de Carvalho

ABG

Ferreira Costa

Fuziy

, et al. Investigation on the relationship of dimensions of the maxillary sinus drainage system with the presence of sinusopathies: a cone beam computed tomography study. Arch Oral Biol. 2018;94:78-83. doi:10.1016/j.archoralbio.2018.06.021

16.

Dağıstan

Cengiz

Haberal Can

İlknur

. The relationship between maxillary sinus retention cysts and nasal septum. J Surg Med. 2021;5(7):687-690. doi:10.28982/josam.928949

17.

Laçin

Yalçın

Demirkol

. Evaluation of the angulation of the nasal septum deviation as an anatomical variation for increased frequency of antral pseudocyst: a cone-beam computed tomography study. Folia Morphol. 2023;82(1):158-165. doi:10.5603/FM.a2021.0127

18.

Nemati

Jafari-Pozve

Aryanezhad

. Association between mucous retention cyst of paranasal sinuses and nasal septum deviation. Adv Oral Maxillofac Surg. 2023;10:100415. doi:10.1016/j.adoms.2023.100415

19.

Atsal

Demir

Yildirim

Edizer

Olgun

. The relationship between degree of nasal septum deviation with sinonasal structures and variations. J Craniofac Surg. 2022;33(5):e447-e449. doi:10.1097/SCS.0000000000008274

20.

Lee

Park

Cha

Moon

Kim

. Does nasal septal deviation and concha bullosa have effect on maxillary sinus volume and maxillary sinusitis? A retrospective study. Taehan Yongsang Uihakhoe Chi. 2020;81(6):1377-1388. doi:10.3348/jksr.2019.0169

21.

Balikci

Gurdal

Celebi

Ozbay

Karakas

. Relationships among concha bullosa, nasal septal deviation, and sinusitis: retrospective analysis of 296 cases. Ear Nose Throat J. 2016;95(12):487-491. doi:10.1177/014556131609501209

22.

Yenigun

Fazliogullari

Gun

Uysal

Nayman

Karabulut

. The effect of the presence of the accessory maxillary ostium on the maxillary sinus. Eur Arch Otorhinolaryngol. 2016;273(12):4315-4319. doi:10.1007/s00405-016-4129-8

23.

Serindere

Gunduz

Avsever

. The relationship between an accessory maxillary ostium and variations in structures adjacent to the maxillary sinus without polyps. Int Arch Otorhinolaryngol. 2022;26(4):e548-e555. doi:10.1055/s-0042-1742325

24.

Han

. Anatomical characteristics of the accessory maxillary ostium in three-dimensional analysis. Medicina (Kaunas). 2022;58(9):1243. doi:10.3390/medicina58091243

25.

Orhan Soylemez

Atalay

. Investigation of the accessory maxillary ostium: a congenital variation or acquired defect? Dentomaxillofac Radiol. 2021;50(6):20200575. doi:10.1259/dmfr.20200575

26.

Motamedi

Torkzadeh

Haerian

. Investigation of the frequency of accessory ostium in the maxillary sinus in patients referred to the radiology department of the faculty of dentistry, Azad University of Isfahan in 2021-2022. J Shahid Sadoughi Uni Med Sci. 2023;30(12):4175-84. doi:10.18502/ssu.v30i12.11964

27.

Tiwari

Goyal

. Role of concha bullosa in chronic rhinosinusitis. Indian J Otolaryngol Head Neck Surg. 2019;71(1):128-131. doi:10.1007/s12070-018-1497-y

28.

Zinreich

. Paranasal sinus imaging. Otolaryngol Head Neck Surg. 1990;103(5 (Pt 2)):863-869. doi:10.1177/01945998901030S505

29.

Kalaiarasi

Ramakrishnan

Poyyamoli

. Anatomical variations of the middle turbinate concha bullosa and its relationship with chronic sinusitis: a prospective radiologic study. Int Arch Otorhinolaryngol. 2018;22(3):297-302. doi:10.1055/s-0038-1625978

30.

Wadhwa

Sharma

Garg

Dutta

. Concha bullosa: types and relationship with chronic sinusitis. Int J Otorhinolaryngol Head Neck Surg. 2017;3(3):482-485. doi:10.18203/issn.2454-5929.ijohns20172651

31.

Paşaoğlu

Toprak

Üstüner

Temel

Özer

. Are variations of paranasal sinuses and infundibular trace length responsible for development of maxillary sinusitis. OMICS J Radiol. 2017;6(4):1000270. doi:10.4172/2167-7964.1000270

32.

Yousefi

Dalili Kajan

Jalali

Khosravifard

Rafiei

. Computed tomographic comparison of length, width and angulation of ethmoidal infundibulum in patients with and without maxillary sinusitis. Indian J Otolaryngol Head Neck Surg. 2022;74(Suppl 2):1220-1231. doi:10.1007/s12070-020-02290-1

33.

Bhattacharyya

. Do maxillary sinus retention cysts reflect obstructive sinus phenomena? Arch Otolaryngol Head Neck Surg. 2000;126(11):1369-1371. doi:10.1001/archotol.126.11.1369

34.

Harar

Chadha

Rogers

. Are maxillary mucosal cysts a manifestation of inflammatory sinus disease? J Laryngol Otol. 2007;121(8):751-754. doi:10.1017/S0022215107005634

35.

Albu

. Symptomatic maxillary sinus retention cysts: should they be removed? Laryngoscope. 2010;120(9):1904-1909. doi:10.1002/lary.21040

36.

Rodrigues

de Arruda

JAA

Silv

, et al. Antral pseudocysts of the maxillary sinus: relationship between radiographic and clinical features. Journal of Oral Diagnosis.2017;2(1):1-7. doi:10.5935/2525-5711.20170042

37.

Jafari-Pozve

Roshanzamir

. Association between the seasonal changes and mucous retention cyst of maxillary antrum in cone beam computed tomography images in a sample population of Isfahan, Iran. Indian J Dent Res. 2018;29(4):410-413. doi:10.4103/ijdr.IJDR_11_17