Endoscopic management of uncommon benign maxillary sinus lesions: a case series

Introduction

Background

The pyramidal-shaped maxillary sinus is considered the largest of the four paranasal sinuses within the human skull (1). These sinuses play a debated yet important role in craniofacial function, including reducing skull weight, increasing resonance of voice, and warming and humidifying inhaled air (2). While chronic rhinosinusitis remains the most common cause of sinonasal complaints, various benign osseous and odontogenic lesions may mimic or overlap in their clinical presentation. Such lesions are often identified accidentally on imaging or during the evaluation of refractory sinus diseases and require precise distinction by radiological and histological assessment to ensure appropriate management (3).

Rationale and knowledge gap

Fibrous dysplasia is a benign, non-neoplastic fibro-osseous disorder characterized by replacement of the normal bone with abnormal fibrous tissue and immature woven bone. It accounts for approximately 70–80% of fibrous dysplasia cases and most commonly manifests in a monostotic form, involving a single bone. The craniofacial bone, particularly the maxilla, is frequently affected and may result in a range of symptoms depending on the lesion location and size, including postnasal drip or headache (4).

While fibrous dysplasia is a recognized cause of persistent sinonasal symptoms due to osseous expansion, osteomas represent another major benign osseous lesion of the paranasal sinuses with similar clinical manifestations. Osteomas are slow-growing benign tumors composed of mature compact or cancellous bone. They most commonly arise in the frontal sinus but may also occur in the maxillary sinus, albeit less frequently (5).

Another uncommon yet locally aggressive maxillary sinus pathology is ameloblastoma, a benign odontogenic tumor that originates predominantly from epithelial remnants of the dental lamina (6). Although more frequently diagnosed in the mandible, maxillary ameloblastomas pose distinct challenges because of the complex anatomy and thin bone architecture of the maxilla (7).

Dentigerous cysts typically originate from the dental follicle and are frequently associated with ectopic or unerupted teeth. When they extend into the maxillary sinus, they may contribute to chronic maxillary sinusitis. Bilateral dentigerous cysts and ectopic teeth within the maxillary sinuses are rare; however, they can result in nasal obstruction and recurrent infections (8,9).

Objective

This case series aims to highlight the varied presentations, diagnostic pathways, and surgical approaches of four distinct benign lesions of the maxillary sinus: fibrous dysplasia, osteoma, ameloblastoma, and bilateral dentigerous cysts with ectopic teeth. We present this article in accordance with the AME Case Series reporting checklist (available at https://acr.amegroups.com/article/view/10.21037/acr-2025-239/rc).

Case presentation

Methods

This study was designed as a case series conducted at a tertiary care hospital. All patients presenting with unique lesions of the maxillary sinuses were included, while common maxillary sinus pathologies and malignant cases were excluded. The hospital setting provided an academic referral environment with access to comprehensive diagnostic and management facilities. Relevant patient characteristics, including clinical history and comorbidities, were documented. Eligibility criteria required a minimum follow-up of six months to ensure adequate outcome assessment, and only cases fulfilling these criteria were involved. Participants were identified through hospital records and case documentation, with consecutive inclusion of all eligible patients during the study period. All procedures performed in this study were in accordance with the ethical standards of the institutional and/or national research committee(s) and with the Declaration of Helsinki and its subsequent amendments. Written informed consent was obtained from all patients for the publication of this case series and accompanying images. A copy of the written consent is available for review by the editorial office of this journal.

Case 1: fibrous dysplasia of the maxillary sinus presenting as refractory sinusitis

A 31-year-old woman, presented with a 6-month history of persistent headache, facial pain, and postnasal drip that was unresponsive to standard medical treatment. Endoscopic nasal examination was unremarkable, with no notable nasal or craniofacial abnormalities detected. A computed tomography (CT) scan of the paranasal sinuses revealed left maxillary sinusitis associated with fibro-osseous lesion occupying the left maxillary sinus (Figure 1). The radiological features were suggestive of fibrous dysplasia.

Figure 1 CT scan of the paranasal sinuses revealed left maxillary sinusitis and a fibro-osseous lesion occupying the left maxillary sinus. CT, computed tomography.

The patient underwent endoscopic sinus surgery, including bilateral middle meatus antrostomy and debulking biopsy of the left maxillary bony lesion. Histopathological analysis confirmed the diagnosis of fibrous dysplasia. At 6 months of postoperative follow-up, the patient was symptom-free with radiologically stable disease and expressed satisfaction with the overall management and clinical outcome. However, the relatively short duration of follow-up is acknowledged as a limitation in assessing long-term disease behavior.

Case 2: benign maxillary sinus osteoid lesions in a patient with multiple myeloma

A 41-year-old female with a known case of multiple myeloma [immunoglobulin G (IgG) kappa type], stage II, was referred to the otorhinolaryngology clinic following an incidental radiological finding of right maxillary sinus calcification. The patient had previously undergone first-line therapy with bortezomib, lenalidomide, and dexamethasone, followed by high-dose melphalan and autologous stem cell transplantation. Her sinonasal endoscopic examination was unremarkable. CT scan of the paranasal sinuses demonstrated an aggressive-appearing calcified lesion within the right maxillary sinus, associated with bony destruction and a retro-antral soft tissue component (Figure 2). Given the patient’s oncologic history and the destructive radiologic features, the differential diagnosis included malignancy, osteomyelitis, medication-related osteonecrosis of the jaw (MRONJ), and benign fibro-osseous lesions.

Figure 2 CT scan of the paranasal sinuses demonstrated an aggressive-appearing calcified lesion in the left maxillary sinus with bony destruction and a retro-antral soft tissue component. CT, computed tomography.

As part of her workup, the patient underwent right maxillary antrostomy with biopsy of the bony lesion in the right maxillary sinus. Histopathological examination revealed benign osteoid tissue with fibrous stroma and no evidence of malignancy. Notably, detailed information regarding prior exposure to antiresorptive agents, dental extractions, or persistent exposed bone was unavailable, and therefore MRONJ could not be definitively excluded based on clinical criteria alone. In view of the benign histopathologic findings, absence of clinical progression, and the patient’s asymptomatic status, a conservative management strategy with close radiologic and endoscopic surveillance was adopted. Over a follow-up period of 2 years, the lesion remained stable with no evidence of progression, supporting conservative observation in this case. Also, the patient expressed satisfaction with the overall management and clinical outcome.

Case 3: recurrent maxillary sinus ameloblastoma in a young adult

A 27-year-old male with a known history of anxiety disorder presented with complaints of bilateral nasal obstruction and intermittent right-sided facial tenderness in his initial presentation. He denied any history of trauma and reported preserved olfactory function along with occasional nasal discharge. Nasal endoscopy showed a bleeding area at the right maxillary sinus opening with a dry clot and no active bleeding; the left side remained intact. At the same initial presentation, CT scan of the paranasal sinuses showed right mucocele. One week later, the patient underwent resection of a right maxillary sinus mass, and histopathological analysis confirmed the diagnosis of ameloblastoma.

Six months postoperatively, the patient reported a foul-smelling nasal discharge and facial pressure on the right side. On examination, nasal endoscopy revealed patent sinuses with mild discharge and a mass located on the floor of the right nasal cavity. A follow-up CT scan with contrast of the paranasal sinuses in his follow-up visit showed interval progression of the biopsy-proven ameloblastoma, with further extension into the right nasal cavity and infiltration of the greater and lesser right palatine canals, reaching the inferior margin of the left pterygopalatine fossa (Figure 3A,3B). Further evaluation with contrast-enhanced magnetic resonance imaging (MRI) revealed a multiloculated, mixed cystic and solid expansile lesion centered in the right maxillary sinus with extension into the right nasal cavity. The lesion showed infiltration of the alveolar process of the maxilla, destruction of the right pterygoid pillar, involvement of the right aspect of the hard palate, and significant bone thinning with possible dehiscence of the lateral maxillary wall. There was also significant effacement of the right retro-antral fat. Also, there was no extension into the orbits, masticator space, or pterygopalatine fossa was identified, and no evidence of perineural spread was seen. Following multidisciplinary tumor board discussion after radiologic progression, the patient required open surgical resection. However, due to the unavailability of obturator-based or free flap reconstruction options at the treating institution at that time, the patient was referred to a tertiary care center for further surgical management.

Figure 3 A coronal CT scan showing (A) and (B) mixed cystic and solid expansile lesion centered in the right maxillary sinus with extension into the right nasal cavity. CT, computed tomography.

Case 4: bilateral dentigerous cysts with ectopic tooth in the maxillary sinus

A 31-year-old male was referred to the otorhinolaryngology clinic as a known case of chronic sinusitis, presenting with facial pain over the upper jaw region and postnasal drip for 6 months prior to presentation. There was no history of trauma. Clinical examination revealed no craniofacial abnormalities, dental anomalies, clavicular deformities, or skeletal abnormalities suggestive of an underlying syndromic condition. Endoscopic nasal examination was unremarkable except for a left septal spur. A CT scan of the paranasal sinuses revealed bilateral cystic lesions within the maxillary antra. The right cystic lesion was associated with an ectopic tooth displaced superiorly and medially within the expanded and remodeled ostiomeatal complex (Figure 4A).

Figure 4 Bilateral dentigerous cysts with ectopic tooth in the maxillary sinuses. (A) Coronal CT scan of the paranasal sinuses revealed bilateral cystic lesions in the maxillary antra. The right cystic lesion was noted to displace an ectopic tooth superiorly and medially in the region of the expanded, remodeled ostiomeatal complex. (B) Intraoperative endoscopic view showing an ectopic tooth found impacted in the medial wall of the right maxillary sinus, obstructing natural drainage, (C) the right middle meatus was filled with frank pus, which was drained. CT, computed tomography.

The patient underwent bilateral endoscopic middle meatal antrostomies, which revealed large bilateral cystic masses completely occupying both maxillary sinuses. An ectopic tooth was identified impacted along the medial wall of the right maxillary sinus, obstructing normal drainage. The right middle meatus contained frank purulent discharge, which was drained (Figure 4B). Based on the clinical, radiologic, and intraoperative findings, a diagnosis of bilateral dentigerous cysts associated with ectopic teeth was established. The ectopic molar tooth was removed endoscopically, followed by dissection and excision of both cysts (Figure 4C). The patient was followed up for 1 year postoperatively and remained asymptomatic with no evidence of recurrence. Moreover, the patient was satisfied with both the therapeutic approach and the outcome.

Discussion

Benign maxillary sinus lesions, although rare, pose significant diagnostic and management challenges due to their various manifestations and overlapping symptomatology. This case series includes four distinct entities: bilateral dentigerous cysts, osteoma, ameloblastoma, and fibrous dysplasia. Each case reveals distinct radiologic, histopathologic, and surgical aspects that may align with, and occasionally differ from, previously reported cases.

As described in Case 1, fibrous dysplasia usually manifests as a monostotic condition and accounts for approximately 7% of benign bone tumors affecting the maxilla and other craniofacial bones. It is most frequently diagnosed in individuals between 10 and 30 years of age, with no strong sex predilection. Imaging is crucial to confirm the diagnosis of fibrous dysplasia since its clinical symptoms, which include facial asymmetry, discomfort, and nasal obstruction, are sometimes vague. The postnasal drip and facial discomfort observed in this study were consistent with previous studies identifying persistent sinonasal symptoms as the predominant presentation of maxillary fibrous dysplasia (3,4). CT imaging typically demonstrates a characteristic ground-glass appearance, as seen in our illustration, and surgical debulking by endoscopic technique remains an effective and minimally invasive treatment for symptomatic lesions with limited bone involvement (10). Prognosis is generally good, with rare malignant transformation (<1%) and low recurrence rates following endoscopic resection.

Osteomas are slow-growing benign tumors that most commonly affect males aged 30 to 50 years (11). While osteomas account for more than half of all benign paranasal sinus tumors, they represent less than 2% of tumors in the maxillary sinus and up to 96% of those occurring in the frontal sinus (12). Our patient, a 41-year-old woman with a history of multiple myeloma, had a right maxillary osteoid lesion incidentally discovered. Given her oncologic background, it was essential to exclude plasmacytoma or metastatic bone involvement. Benign osteoid with fibrous stroma was confirmed by histopathology. In accordance with previously published recommendations, which were against surgical intervention for asymptomatic, non-obstructive osteomas, observation was chosen due to the absence of symptoms and radiologic stability over a 2-year follow-up period (13). Long-term prognosis is excellent, with rare recurrence following complete excision and minimal progression under conservative management.

Ameloblastoma, albeit benign, is locally invasive with a recurrence rate ranging from 15% to 35% depending on surgical margins as stated by Carlson and Marx (14). Maxillary involvement is uncommon (10–15%) but associated with increased severity because of the thin cortical bone and proximity to the skull base (6). In our case, imaging revealed tumor extension into the nasal cavity and palatine canals 6 months after initial surgery, indicating recurrence. The aggressive behavior and early recurrence necessitated open surgical resection, as recommended by Pogrel and Montes, who contend that open surgery offers superior margin control in maxillary ameloblastomas (7). In this study, we present a case of maxillary ameloblastoma initially managed with an endoscopic approach, which was subsequently complicated by disease recurrence, necessitating definitive open surgical resection. Endoscopic removal of maxillary ameloblastoma carries a significant risk of recurrence due to the tumor’s infiltrative growth pattern and the inherent limitations of endoscopic techniques in achieving adequate oncologic margins, underscoring the need for cautious patient selection and close follow-up (15-17). This highlights that not all benign maxillary sinus lesions can be successfully treated using an endoscopic approach, and that caution should be exercised when considering this technique in similar cases.

The second most prevalent odontogenic cyst, dentigerous cysts, usually develop in the second to third decades of life and are frequently linked to impacted third molars (18). Bilateral involvement of the maxillary sinuses is rare, particularly in non-syndromic individuals. Our 31-year-old male presented with facial discomfort and nasal discharge secondary to bilateral maxillary cysts, along with an ectopic molar in the right sinus that was obstructing the ostiomeatal complex. Dentigerous cysts typically appear radiographically as well-defined unilocular radiolucencies surrounding the crown of an unerupted tooth (9). Endoscopic surgical excision was selected to minimize morbidity and preserve surrounding structures. This strategy has been associated with favorable outcomes in similar cases (8). Prognosis is excellent with complete removal; recurrence is uncommon and typically associated with syndromic disease or incomplete excision.

This case series has several limitations that should be acknowledged. First, its retrospective design may introduce bias related to record completeness and the accuracy of documentation. Second, the small number of cases limits the generalizability of the findings. In addition, malignant maxillary sinus lesions were excluded, which limits the scope of applicability to benign conditions only. Finally, not all possible maxillary sinus pathologies were represented in the study, and the spectrum of lesions discussed does not encompass the full range of potential clinical presentations.

Conclusions

Benign lesions of the maxillary sinus, although uncommon and often presenting with nonspecific sinonasal symptoms, require meticulous radiographic and histopathological evaluation to ensure accurate diagnosis and appropriate treatment planning. This case series illustrates the diversity of such lesions, including fibrous dysplasia, osteoma, ameloblastoma, and dentigerous cysts, and highlights the role of endoscopic techniques in their diagnosis and management. Surgical strategy should be individualized based on lesion histology, anatomical extent, and risk of recurrence. While endoscopic approaches demonstrate high success rates and offer a safe, effective, and minimally invasive option for many maxillary sinus lesions, they are not universally applicable. In particular, maxillary ameloblastoma poses unique challenges due to its locally aggressive and infiltrative behavior, making endoscopic management a less favorable option and underscoring the need for heightened caution and careful surgical selection. Open resection and multidisciplinary planning may therefore be required for aggressive or recurrent lesions. Early recognition and timely intervention remain essential for optimizing outcomes and minimizing complications or recurrence. Further multicenter studies with larger cohorts are warranted to validate these observations and refine treatment algorithms.

Acknowledgments

None.

Footnote

Reporting Checklist: The authors have completed the AME Case Series reporting checklist. Available at https://acr.amegroups.com/article/view/10.21037/acr-2025-239/rc

Peer Review File: Available at https://acr.amegroups.com/article/view/10.21037/acr-2025-239/prf

Funding: None.

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://acr.amegroups.com/article/view/10.21037/acr-2025-239/coif). The authors have no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. All procedures performed in this study were in accordance with the ethical standards of the institutional and/or national research committee(s) and with the Declaration of Helsinki and its subsequent amendments. Written informed consent was obtained from all patients for publication of this case series and accompanying images. A copy of the written consent is available for review by the editorial office.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

References

1. Iwanaga J, Wilson C, Lachkar S, et al. Clinical anatomy of the maxillary sinus: application to sinus floor augmentation. Anat Cell Biol 2019;52:17-24. [Crossref] [PubMed]
2. Cappello ZJ, Minutello K, Dublin AB. Anatomy, Head and Neck, Nose Paranasal Sinuses. Treasure Island, FL, USA: StatPearls Publishing; 2024.
3. Subramaniam V, Herle A. Fibrous dysplasia of the maxillary sinus: case report. RSBO 2011;7:366-8.
4. Stefanovic P, Djeric D. Maxillary sinus fibrous dysplasia. Journal of Rhinology 1998;5:152-4.
5. Sigdel B, Neupane B, Pokhrel A, et al. Asymptomatic Massive Fibrous Dysplasia Obliterating Maxillary Sinus Extending to the Skull Base: a Case Report and Review of Literature. Journal of College of Medical Sciences-Nepal 2022;18:178-81.
6. McClary AC, West RB, McClary AC, et al. Ameloblastoma: a clinical review and trends in management. Eur Arch Otorhinolaryngol 2016;273:1649-61. [Crossref] [PubMed]
7. Pogrel MA, Montes DM. Is there a role for enucleation in the management of ameloblastoma? Int J Oral Maxillofac Surg 2009;38:807-12. [Crossref] [PubMed]
8. Buyukkurt MC, Omezli MM, Miloglu O. Dentigerous cyst associated with an ectopic tooth in the maxillary sinus: a report of 3 cases and review of the literature. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2010;109:67-71. [Crossref] [PubMed]
9. Lombroni LG, Farronato G, Santamaria G, et al. Ectopic teeth in the maxillary sinus: a case report and literature review. Indian J Dent Res 2018;29:667-71. [Crossref] [PubMed]
10. Kochanowski NE, Badry MS, Abdelkarim AZ, et al. Radiographic Diagnosis of Fibrous Dysplasia in Maxilla. Cureus 2018;10:
11. Sofokleous V, Maragoudakis P, Kyrodimos E, et al. Management of paranasal sinus osteomas: A comprehensive narrative review of the literature and an up-to-date grading system. Am J Otolaryngol 2021;42:102644. [Crossref] [PubMed]
12. Savić DL, Djerić DR. Indications for the surgical treatment of osteomas of the frontal and ethmoid sinuses. Clin Otolaryngol Allied Sci 1990;15:397-404. [Crossref] [PubMed]
13. Arslan HH, Tasli H, Cebeci S, et al. The Management of the Paranasal Sinus Osteomas. J Craniofac Surg 2017;28:741-5. [Crossref] [PubMed]
14. Carlson ER, Marx RE. The ameloblastoma: primary, curative surgical management. J Oral Maxillofac Surg 2006;64:484-94. r. [Crossref] [PubMed]
15. Sehdev MK, Huvos AG, Strong EW, et al. Cancer 1974;33:324-33. [Crossref] [PubMed]
16. Evangelou Z, Zarachi A, Dumollard JM, et al. Maxillary Ameloblastoma: A Review With Clinical, Histological and Prognostic Data of a Rare Tumor. In Vivo 2020;34:2249-58. [Crossref] [PubMed]
17. Zwahlen RA, Grätz KW. Maxillary ameloblastomas: a review of the literature and of a 15-year database. Journal of Cranio-Maxillofacial Surgery 2002;30:273-9.
18. Shear M, Speight P. Cysts of the Oral and Maxillofacial Regions. 4th edition. Wiley-Blackwell; 2007.