Dentomaxillofacial Radiology (2009) 38, 48-52
© 2009 British Institute of Radiology
doi: 10.1259/dmfr/95388644
Complex odontoma associated with dentigerous cyst in maxillary sinus: case report and computed tomography features
MA Sales*,1 and
MG Cavalcanti2,3
1Department of Radiology, College of Dentistry, University of São Paulo, Lauro Wanderley Hospital, Federal University of Paraiba, João Pessoa, PB, Brazil; 2Department of Radiology, College of Dentistry, University of São Paulo, Brazil; 3Department of Radiology, College of Medicine, University of Iowa, Iowa City, USA
*Correspondence to: Dr Marcelo Cavalcanti, University of São Paulo, Faculty of Odontology, Department of Radiology, Av. Prof. Lineu Prestes 2227, São Paulo, SP 05508-900, Brazil. E-mail: mgpcaval{at}usp.br
Received 25 September 2007;
revised 24 December 2007;
accepted 8 January 2008
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Abstract
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Tumoural and cystic lesions are common findings in the daily practice of dental professionals and maxillofacial radiologists. However, simultaneous lesions are rare and represent a diagnostic challenge to overcome. Among tumoural pathologies, odontomas are the most common odontogenic tumour of the jaws. Cystic transformation or development from the tumoural capsule are well recognized in situations such as ameloblastomas originated from a dentigerous cyst. Otherwise, despite literature reports, dentigerous cysts arising from odontomas are very rare and could lead to misdiagnosis. Here, we report a case of a complex odontoma associated with a dentigerous cyst in the maxillary sinus, focussing on the tomographic features and a differential imaging approach to the diagnosis of these lesions.
Keywords: odontogenic tumour, cysts, computed tomography
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Introduction
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Odontomas are the most common of the odontogenic tumours of the jaws. They are mixed tumours, consisting of both epithelial and mesenchymal cells, that present a complete dental tissue differentiation (enamel, dentin, cementum and pulp).1 These lesions are easily removed under local anaesthesia and the prognosis is very good. Additionally, large odontomas are associated with local disturbances such as the eruption delay of permanent teeth and the development of cystic lesions as dentigerous cysts. These cases of simultaneous pathologies are uncommon and diagnosis based on the radiographic appearance of such lesions is a challenge to dental professionals because huge lesions with solid features can mimic pathologies such as fibro-osseous lesions (fibrous dysplasia, ossifying fibroma) and, given the size and localization, can lead to serious damage to maxillofacial structures.2 The purpose of this paper is to describe a case of complex odontoma associated with a dentigerous cyst in the maxillary sinus, particularly the tomographic features, and a differential imaging approach to the diagnosis of these lesions.
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Case report
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A 31-year-old white male was referred to our department to assess an increase of volume in the maxillary vestibular sulcus on his left side. At physical examination, a swelling of the alveolar process with a firm consistency and erasure of the vestibular sulcus were noted. The soft tissue had normal colour and no complaints of pain or inflammatory disease were reported. On periapical and panoramic radiographs, a solid radiopaque glass-like mass was observed involving the left alveolar ridge and the maxillary sinus (Figures 1
and 2). This mass contained in its interior one focal calcification resembling a tooth in the region of the upper maxillary molars. Axial and multiplanar reconstructed (MPR) CT images (Figures 3 and 4) revealed a hyperdense mass extending from the alveolar ridge to the middle third of the maxillary sinus, associated with a hypodense image at the superior aspect of the sinus with extension to the orbital roof and ethmoidal sinus, containing a focal hyperdense image. In the soft tissue window, these features were assigned to one lesion compatible with the cystic image (soft tissue hyperdensity) located at the superior aspect of the sinus. Surgical access to the maxillary sinus was gained under general anaesthesia (Figure 5). At that moment, two distinct encapsulated lesions were observed and completely removed without difficulty. Histopathological examination revealed a complex odontoma associated with a dentigerous cyst. The patient was discharged and was asymptomatic.
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Figure 1 Periapical radiograph depicting huge radiopaque mass at left maxillary molar, involving roots of first and second molars
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Figure 2 Panoramic radiograph depicting well-defined mass in region of left maxillary molars, associated with roots of involved teeth
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Figure 3 Tomographic features of complex odontoma associated with dentigerous cyst (bone window). (a) Axial view – hyperdense image at level of floor of the maxillary sinus depicting destruction of lateral and posterior walls, (b) mixed image revealing a thin halo surrounding hypodense mass causing expansion of medial wall of maxillary sinus (arrows), (c) sagittal view demonstrating involvement of orbital roof and (d) coronal view showing involvement of nasal fossae, orbital roof and ethmoidal cells (arrowheads)
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Figure 4 (a) Axial, (b) coronal and (c) sagittal views depicting filling of maxillary sinus with homogeneous mass (soft tissue window), involving ethmoidal sinus, extending from alveolar ridge to orbital rim. The more hypodense aspect in comparison with adjacent soft tissues is highly suggestive of an associated cystic lesion
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Figure 5 Top image shows the inner aspect of the maxillary sinus during surgical procedure, including two distinct lesions in the left maxillary sinus. Arrowhead, dentigerous cyst; asterisk, complex odontoma. Bottom image presents the surgical specimen showing multiple lesions
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Discussion
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The maxillary sinus is a frequent site for pathologies of odontogenic origin. Due to its close anatomical relationship with teeth and periodontal tissues, inflammatory disease as well as neoplastic and tumourous lesions can occur in this area. On the other hand, asymptomatic disease is a common incidental finding when radiographic evaluation is performed and should be carefully analysed. Maxillary sinus involvement must be carefully assessed because orbital damage and the spreading of associated infections could lead to local and systemic compromise to the patient. Even in cases of benign pathologies, suspicion of maxillary sinus involvement means that radiographic evaluation is mandatory.3
With respect to the radiopaque/mixed (Figures 1
and 2) or hyperdense/hypodense (Figures 3 and 4) radiographic appearance as depicted in our case, many categories of osseous pathologies involving the maxillary sinus and sinusal cavities must be considered, ranging from osseous dysplasia in its various forms (monostotic, craniofacial) to odontogenic lesions (odontomas and dentigerous cyst).1, 4 In this regard, odontomas are the most prevalent tumours in the dental field3 and involvement with the sinus is common. They consist of mixed lesions with epithelial and mesenchymal tissues, which show differentiation into odontogenic tissues such as enamel, dentin, cementum and pulp.5 Despite their unknown aetiology, odontomas are usually discovered during the second and third decades of life.1 Panoramic and periapical images usually show well-defined borders of a similar density to calcified dental tissue, having a ground-glass appearance, and a radiopaque mass occupying the affected maxillary sinus,6 surrounded by a thin radiolucent halo. Although they are usually tooth-sized or smaller, the complex variant can occasionally exhibit considerable growth and extend beyond the maxillary and paranasal sinuses.8
As a result of their odontogenic nature, including epithelial and mesenchymal tissues, odontomas can develop cystic transformation into a dentigerous cyst. This cyst results from the cystic degeneration of the enamel organ after partial or total development of the crown.1 These changes are cited as possible, but are rarely seen in clinical practice. In our case, the radiographic features and very large lesion size were not initially conclusive for diagnostic purposes; a diagnostic hypothesis of fibro-osseous lesions such as fibrous dysplasia and ossifying fibroma was contemplated due to the heterogeneous appearance. Additional radiographic evaluation with CT was necessary to determine the extension and features of the lesion because the two-dimensional limitations of periapical and panoramic images did not allow complete visualization of the maxillofacial complex. In this regard, CT images are necessary not only for evaluation of the lesion itself, but also for localization of associated pathoses and proper treatment planning.9
Imaging features of fibro-osseous lesions are very difficult to distinguish among the large group of similar pathologies such as ossifying fibroma, fibrous dysplasia and others.8 In these cases, CT is an important tool for the differential diagnosis of the above-mentioned lesions.10, 11
In our case, CT images allowed better depiction of the involved structures and all of the paranasal sinuses, revealing in the maxillary sinus and attached to the hyperdense image a second area with a cystic appearance extending from the middle portion of the sinus to the orbital roof. At that point, CT images bore no resemblance to fibrous dysplasia because of the two simultaneous lesions. These features, based on CT images, were critical for the therapeutic approach, allowing perfect planning for the surgical procedure and elucidation of diagnosis. CT is the gold standard, especially for ruling out any suspicion of associated orbital involvement, and revealing the spread and intracranial extension of infectious process. In cases when obstruction of sinus drainage is evident, one should be completely aware of serious complications such as orbital infections, epidural and subdural empyema, meningitis, cerebritis, cavernous sinus thrombosis, brain abscess and death.12
These conditions are associated with pathologies arising from the alveolar process (e.g. odontogenic cysts) and the iatrogenic development of mucocoeles with orbital roof involvement.3
Sinus CT is widely performed in the imaging work-up of sinus pathologies, but it has been criticized for the lack of specificity. Several reports published in surgical journals found that sinus CT findings did not correlate well with a patient's clinical symptoms because the results of sinus CT can be normal and associated with many diverse conditions such as viral infections or extremely cold environmental conditions.13 In our specific case, the existence of a hyperdense halo surrounding an area with a low attenuation coefficient was compatible with the hypothesis of some associated lesion or the existence of two simultaneous cystic lesions, visualized only with the aid of CT. At that point, as odontoma was associated with another lesion with cystic features, a dentigerous cyst could probably be the result of a cystic degeneration and should be chosen as the probable diagnosis. This was confirmed following the surgical removal of two distinct lesions in the interior of the maxillary sinus. Histopathology showed complex odontoma associated with a dentigerous cyst.
When the diagnosis has been established, odontomas must be removed as they may cause cystic formation with later delay of permanent dentition and bone destruction.14 Reports of large maxillofacial involvement and head and neck infections are also associated with dentigerous cysts.2
Furthermore, despite their benign nature, these lesions are well recognized by their growth pattern and should be completely removed to avoid secondary complications and possible sequelae for the patient, with an excellent prognosis following surgery.
Despite some reports in the literature regarding cyst development from tumoural lesions, such situations are very difficult to distinguish in daily practice. The appearance of associated lesions represents a pitfall to radiologists because the patterns are inconclusive and could lead to erroneous interpretation based solely on conventional images, thus making additional CT evaluation mandatory. This conduct is crucial for avoiding mistakes that could compromise the treatment and prognosis.
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Acknowledgments
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FAPESP/SP (São Paulo, Brazil) for granting a post-doctoral fellowship (2006/05251-8) to the author Marcelo Augusto Oliveira Sales.
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References
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Abstract
Introduction
