|Year : 2014 | Volume
| Issue : 1 | Page : 26-29
Stafne bone cavity incidentally ''Twice'' diagnosed on panoramic radiographs
Ulkem Aydin1, Yener Oguz2
1 Department of Dentomaxillofacial Radiology, Faculty of Dentistry, Baskent University, Ankara, Turkey
2 Department of Oral and Maxillofacial Surgery, Faculty of Dentistry, Baskent University, Ankara, Turkey
|Date of Web Publication||2-Jun-2014|
11. Sokak no 26, Bahcelievler, Ankara
Source of Support: None, Conflict of Interest: None
A 63-year-old male patient admitted to another hospital for prosthetic restoration. On the panoramic radiograph a lesion was detected on the right mandible and he was referred for a cone beam computed tomography (CBCT) examination. The patient then admitted to our clinic for the diagnosis of this lesion. Review of the dental records revealed that a panoramic radiograph and a maxillofacial computed tomography scan were made about 10 years ago, and a Stafne bone cavity (SBC) was diagnosed. Moreover, a follow-up panoramic radiograph was made about 5 years ago. Despite the explanation given, the patient requested the CBCT examination in a private imaging center. The imaging features of the lesion were the same. In order to protect the patients from unnecessary radiation, the clinicians should make every effort to prevent duplicate imaging, and X-ray based advanced imaging techniques should be reserved for selected cases.
Keywords: Imaging, radiography, Stafne bone cavity
|How to cite this article:|
Aydin U, Oguz Y. Stafne bone cavity incidentally ''Twice'' diagnosed on panoramic radiographs. J Oral Maxillofac Radiol 2014;2:26-9
|How to cite this URL:|
Aydin U, Oguz Y. Stafne bone cavity incidentally ''Twice'' diagnosed on panoramic radiographs. J Oral Maxillofac Radiol [serial online] 2014 [cited 2020 Jan 17];2:26-9. Available from: http://www.joomr.org/text.asp?2014/2/1/26/133564
| Introduction|| |
Pathoses and anomalies located inferior to the mandibular canal are thought to be non-odontogenic.  One of the best known of these is the Stafne bone cavity (SBC). The defect contains salivary gland or adipose soft tissue. SBC affects the male gender to a signiﬁcantly greater extent and most diagnosed in the ﬁfth and sixth decades of life. SBC can be easily identified by the radiographic features, but sometimes it is considered a suspicious lesion by the dentists and may be a concern for patients. This asymptomatic lesion is located inferior to the mandibular canal between the mandibular angle and molar region. An oval or rounded unilocular radiolucent image 1-2 cm in diameter with a well-defined corticated outline is observed radiographically. ,,,
As the lesion is asymptomatic, usually the diagnosis is made incidentally on routine radiographic examinations. Besides the conventional techniques such as panoramic radiography: magnetic resonance imaging (MRI), computed tomography (CT) and more recently, cone beam computed tomography (CBCT) are used to examine the lesion.  Sialography with plain radiographs or CBCT are other imaging modalities. ,
In this case report, panoramic radiography, computed tomography and CBCT imaging features of a posterior variant of SBC taken in 10 years are compared and the utility of these imaging techniques are discussed.
| Case Report|| |
A 63-year-old male patient was admitted to the oral diagnosis clinic at Baskent University in 2012, for a second opinion on the lesion that was detected on the panoramic radiograph. The patient stated that, he recently attended a dental health center for renewal of his prosthetic restorations. After the clinical examination, a panoramic radiograph was made there on which a lesion was noticed on the right side of the mandible and the clinician referred the patient for a cone beam computed tomography scan. The patient then attended our oral diagnosis clinic for the diagnosis and treatment of this lesion. At the time of attendance, he was systemically healthy; extraoral and intraoral examination did not reveal any abnormality.
Examination of the current panoramic radiograph revealed a unilocular, roughly circular radiolucent lesion with radiopaque borders that was located on the right mandible, between the inferior dental canal and the mandibular cortex [Figure 1]. Review of the dental records of the patient revealed that, at the end of 2001, the patient attended a dental health center for implant placement and construction of implant-supported prosthetic restoration. After the clinical examination, a panoramic radiograph was made there and the dentist noticed a lesion on the right mandible. In 2002, the patient attended Baskent University for a second opinion. The clinician requested the patient to bring the panoramic radiograph but as the radiograph was unavailable, a new one was made. On the panoramic radiograph made in 2002, a rounded radiolucent lesion anterior to the mandibular angle was evident. The diameter of the lesion was approximately 1.5 cm. [Figure 2]. The records also indicated that the patient was referred for computed tomography examination. According to the CT report, a spiral CT scanning without contrast medium was made and axial sections of the mandible with 2 mm of thickness were obtained. The lesion was located at the angle of the right mandible and sized 0.5 × 1 cm. The cavity was filled with fat density material and the contour was regular. The medial part of the lesion was described as "open." The lesion was considered to be consistent with a Stafne bone cavity. The patient was scheduled for a follow-up appointment. According to the records on the patient file, in 2005, the patient was admitted to the oral diagnosis clinic complaining of loose dentures. Another panoramic radiograph was made at that time and it was noted that the lesion exhibited no dimensional change in 3 years.
|Figure 1: The panoramic radiograph made in 2001. The lesion is located close to the mandibular angle, between the inferior dental canal and the mandibular cortex. The cortical outline is regular and radiopaque|
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|Figure 2: The panoramic radiograph made in 2012. The lesion seems larger; the cortical outline is thin and less regular when compared with the previous panoramic radiograph|
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Regarding the present and previous examinations and imaging features, the patient was told that the condition does not require treatment. However, as the patient could not recall the previous examinations and the diagnosis, and as he believed that the lesion had enlarged, he attended a private dental imaging center with the CBCT request form given at the dental health center. Then he came back to our faculty for the interpretation of the CBCT images.
The CBCT examination revealed that the cavity was 12.2 × 5.1 × 10.9 mm in size and the lesion was located anterior to the mandibular angle, between the inferior dental canal and the mandibular cortex. In addition, the lingual depression had a continuous cortical outline [Figure 3]. It was decided that there was no dimensional change in 10 years and the other imaging features were also the same.
|Figure 3: Cone-beam CT images. The cavity is 12.2 × 5.1 × 10.9 mm3 in size (a, c, d). The lesion is located anterior to the mandibular angle, between the inferior dental canal and the mandibular cortex (b, d). The lingual depression has a continuous cortical outline (c, d)|
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| Discussion|| |
SBC is generally diagnosed incidentally on routine panoramic radiographs. SBC has two major variants related to the location of the defect. The posterior variant is located below the inferior dental canal between the mandibular angle and the molar teeth and it is concluded to occur as a result of the pressure produced by submandibular gland and related structure.  Although the diagnosis is easy when the lesion is at the posterior region; in some cases such as atypical shaped, multiple, bilateral or anteriorly located defects, it may be difficult to diagnose SBC and advanced imaging techniques are required. ,,, In our case, the defect was located anterior to the mandibular angle, between the inferior dental canal and the mandibular cortex, which is the typical location for the posterior variant of SBC.
In many cases panoramic radiographs give adequate information on the presence and extent of a Stafne bone cavity.  On the other hand, due to positioning and exposure errors, the location, shape and density of the lesion may change and this may result in misinterpretation of the radiographic features revealed on initial or follow-up radiographs. Positional errors may lead to magnification and limit dimensional accuracy on panoramic radiographs. The differences in patient positioning may result in a difference in the traversing of X-rays from the periphery of the lesion and as a consequence, definition of the boundary of the lesion may change. ,, In the present case, the final panoramic radiograph revealed a larger defect compared to the first one and the patient thought that the lesion had enlarged. In addition, the lesion boundary was thinner and was not very distinct as in the first radiograph. We conclude that the aforementioned reasons resulted in the alterations revealed in the two panoramic radiographs. Therefore, dentists should know the imaging principles of this technique and errors that can occur in panoramic radiography in order to correctly interpret the follow-up radiographs and to explain the differences to the patients.
CT or MRI can be used to obtain three-dimensional images in order to determine the shape and size of the lesion and to confirm the content of the lesion. These techniques also reveal the characteristics of the lesion boundary. Axial CT sections show the peripheral origin of the lesion and the preservation of the lingual cortical bone. , SBC is thought to be due to the remodelling of the mandibular cortex around the salivary gland tissue and CT and MRI examinations show content consistent with salivary gland tissue. However, in some of cases, adipose tissue may be detected. ,,, In the case presented, CT imaging revealed that the lesion seen on the panoramic radiograph was a bone cavity and was filled with adipose tissue. CT imaging also enabled the determination of the dimensions of the lesion. Different from CT, MRI does not expose the patient to ionizing radiation and therefore, despite the disadvantages such as the high cost, patient uncomfort and distortion artifacts, in the case presented, MRI might have been preferred to determine the content. ,, Although it is not exactly known why MRI was not made, it may be assumed that this imaging technique is not well adopted by all dental specialists and the clinicians prefer advanced imaging techniques that they are more familiar to.
Cone beam computed tomography (CBCT) is a method with high resolution and low radiation exposure compared to conventional CT techniques, and it was stated that CBCT provides accurate information on the shape, location and size of SBC. , In the case presented, CBCT examination revealed that the size of the lesion did not change during 10 years. Despite the advantages, CBCT examination was unnecessary in the case presented because one initial panoramic radiograph, one CT examination and one follow-up radiograph was made between 2002 and 2005 and the patient was previously diagnosed with SBC. Nonetheless, mandibular bone depressions cannot be considered exclusively as salivary gland-related bone defects. As CBCT does not give soft tissue information, this technique should not be used when the content of the lesion is to be determined. 
No surgical treatment is needed for SBC since these defects are anatomical variants.  Surgical exploration and biopsy may be an option when other pathoses such as salivary gland tumors, central giant cell granuloma, fibrosseous lesions, eosinophilic granuloma and other related lesions are suspected.  In the present case, the lesion dimensions recorded in the CT report and the measurements made on CBCT images revealed that the size of the lesion did not change in 10 years. Therefore, it was concluded that the lesion was not pathologic and no surgical operation was made.
Panoramic radiographs may not ensure the patients and inexperienced practitioners regarding to the diagnosis of SBC. In the present case, the patient had four panoramic radiographs in 10 years. In addition, one maxillofacial CT and one CBCT examination were made. One of the panoramic radiographs was made because the previous one was not available. CT examination was made although MRI would have given sufficient information. Lastly, CBCT examination was unnecessary as the case was previously diagnosed and a follow-up radiograph was also obtained.
In radiology, it is still a challenging task to share images across institutions. The dentists should question the patients about previous radiographic examinations, request patients to bring them or they can refer the patients to the dental facility where the previous radiographic examination was made. Digital radiography systems enabled the clinicians to use simple means of sharing image data such as burning it on CDs and e-mailing them. Implementation of systems for sharing of remote data across geographically distant institutions will allow the clinicians to acess previous radiographic images and reports. Cloud-based solutions are also becoming an accepted way for image sharing.  In order to protect the patients from unnecessary radiation, the clinicians should make every effort to use the methods of image sharing and to prevent duplicate imaging, and X-ray based advanced imaging techniques should be reserved for selected cases.
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