|Year : 2015 | Volume
| Issue : 3 | Page : 92-96
Investigation and differential diagnosis of Stafne bone cavities with cone beam computed tomography and magnetic resonance imaging: Report of two cases
Elif Tarim Ertas1, Meral Yircali Atici1, Fahrettin Kalabalik1, Ozlem Ince2
1 Department of Oral and Maxillofacial Radiology, Faculty of Dentistry, İzmir Katip Çelebi University, İzmir, Turkey
2 Department of Radiology, Sifa University Research and Training Hospital, İzmir, Turkey
|Date of Web Publication||27-Nov-2015|
Dr. Elif Tarim Ertas
Aydınlık Evler Mahallesi, Cemil Meriç Caddesi, 6780 Sokak. No. 48, 35640-Çiğli, İzmir
Source of Support: None, Conflict of Interest: None
Stafne bone cavity (SBC), commonly known as Stafne bone cyst or defect is mostly asymptomatic, appearing as a unilateral, round or ovoid, radiolucent defect with thick and corticated border. Defects that are referred as pseudocysts generally occur in mandibular molar region, below the mandibular canal at the lingual side of the mandible and may grow slowly in time. They have been also located lingually in the anterior mandible above the mylohyoid muscle, and on the ascending ramus just inferior to mandibular condyle or very rarely buccal region of the ascending ramus. The aim of this case report is to present two unusual cases of SBC detected incidentally during radiographic examination with cone beam computed tomography and magnetic resonance imaging findings. In the first case, significant enlargement caused vestibular resorption of the buccal cortex, which is a rare finding with SBCs and in the second case the large bone resorption reached up to the mental foramen.
Keywords: Cone beam computed tomography, magnetic resonance imaging, panoramic radiography, salivary gland depression, Stafne bone cavity
|How to cite this article:|
Ertas ET, Atici MY, Kalabalik F, Ince O. Investigation and differential diagnosis of Stafne bone cavities with cone beam computed tomography and magnetic resonance imaging: Report of two cases. J Oral Maxillofac Radiol 2015;3:92-6
|How to cite this URL:|
Ertas ET, Atici MY, Kalabalik F, Ince O. Investigation and differential diagnosis of Stafne bone cavities with cone beam computed tomography and magnetic resonance imaging: Report of two cases. J Oral Maxillofac Radiol [serial online] 2015 [cited 2018 Oct 20];3:92-6. Available from: http://www.joomr.org/text.asp?2015/3/3/92/170617
| Introduction|| |
Stafne bone cavity (SBC), is an asymptomatic bone depression which is referred as pseudocyst without epithelial lining.  In general, they occur in the mandibular molar region, related to the submandibular gland below the mandibular canal. Rarely, they appear apical region of the premolars and canines of the anterior mandible, associated with the sublingual glands above the mylohyoid muscle.  Etiology of SBC is unknown, but the surrounding tissue or facial artery mechanical pressures can be origin of this developmental anomaly. 
Radiographically, they are unilocular, round or ovoid radiolucent cyst like defects with well-defined, thick and corticated border and their diameter size varies 1-3 cm.  Nevertheless they can be seen multilocular with irregular borders. 
The differential diagnosis of mandibular depressions includes several pathologic entities, such as, odontogenic cyst, simple bone cyst, ameloblastoma, hemangioma, myxoma, central giant cell lesion, fibro-osseous lesions, multiple myeloma, eosinophilic granuloma, benign salivary gland tumors, neurogenic tumors, and metastatic disease. ,,, If SBC have well-defined, thick and corticated borders and oval shape under the mandibular canal in contact with the base of the mandible, differential diagnosis can be easy. However, if they are noticed higher or above the mandibular canal and have no connection with the mandibular base with irregular borders, can cause misdiagnose. Computed tomography (CT) or magnetic resonance imaging (MRI) should be useful for differential diagnose.  In this case report, two unusual cases of posterior and anterior Stafne bone cysts are presented with three-dimensional cone-beam CT (CBCT) and MRI findings.
| Case Reports|| |
A 51-year-old male patient was referred to our clinic for routine dental examination and periodontal treatment. The radiolucent area, which was located at the posterior right molar region of the mandible below the inferior dental canal, had been identified on a panoramic radiograph [Figure 1]. The patient had no complaints concerning this region, and his medical history was ordinary and he had no trauma or surgery history of the jaws. At the right posterior region of the mandible and submandibular region, there was no swelling or abnormality. He had no pain during palpation. Along the distribution of the inferior alveolar and mental nerves, revealed intact sensation.
|Figure 1: The radiolucent area, which was located at the posterior right molar region of the mandible below the inferior dental canal on panoramic radiography|
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Stafne bone cavity was considered for the radiolucent area located under the mandibular canal but because of the largeness of the lesion and to view its dimensions and borders, CBCT (NewTom 5G; QR, Verona, Italy) was performed [Figure 2]. Examination of the axial images of the CBCT scan showed a mandibular lingual wall defect at the molar region with vestibular extension, which causes resorption of the vestibular cortex [Figure 2]a. The cross-sectional images presented the invagination of the lingual cortex up to the buccal cortex [Figure 2]b. [Figure 3] shows the three-dimensional (3D) CBCT volume rendering reconstructed images of the patient showed lingual bone defect field.
|Figure 2: (a) The cross-sectional images presented the invagination of the lingual cortex up to the buccal cortex. (b) The axial images of the cone beam computed tomography scan showed a mandibular lingual wall defect at the molar region with vestibular extension|
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|Figure 3: Three-dimensional cone beam computed tomography volume rendering reconstructed images of the patient showed lingual bone defect field|
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In the literature vestibular cortical resorption is an unusual finding so to learn the content of the cavity, MRI was performed. In the defective cavity located in the alveolar arcus two components with different signal intensities were detected. In the T1 fat-saturated, T2 fat saturated, and T1 fat saturated contrasted MRI images, the posterior part of the bone cavity is filled with anteriosuperior part of the submandibular gland. In T1 and T2 sequences, anterior part of the cavity showed hiperintens signals, which is compatible with proteinaceous content in this area. No fatty content was detected in fat saturated sequences in the anterior part [Figure 4].
|Figure 4: (a) Coronal short tau inversion recovery, (b and c) postcontrast axial T1 FSE, images shows that the posterior part of mandibular defect is filled with soft tissue that is continuous and identical in signal with that of submandibular gland, and the anterior part is filled with proteinaceous soft tissue|
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Final diagnose of the lesion was made as a posterior variant of SBC and the patient was informed about the lesion and scheduled follow-up appointments for every 6 months.
A 38-year-old male patient was referred to our clinic for routine dental examination and prosthetic management. A panoramic radiograph of the patient revealed a radiolucent area at the right first and second premolar region of the mandible below the root of the premolars [Figure 5]. The patient's medical and dental history was not contributory. There was no pain and no symptoms such as expansion in this region. Along the distribution of the inferior alveolar and mental nerves, revealed intact sensation. In order to eliminate the diagnosis of the radicular cyst, vitality test was performed, and teeth were vital.
|Figure 5: A panoramic radiograph of the patient revealed a radiolucent area below the root of the premolars|
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We performed CBCT (NewTom 5G; QR, Verona, Italy) scan to the definite, exact location of the lesion and to confirm the diagnosis of the entity [Figure 6]. Two-dimensional multiplanar reconstructed CBCT axial images revealed that the radiolucent area located on the anterior region of the mandible lingually with mental foramen relationship [Figure 6]a. The cross-sectional images showed depression of the lingual cortex below the premolar region without any connection with the apex of premolars [Figure 6]b. 3D CBCT volume rendering reconstructed images revealed a bone defect at the anterior mandible [Figure 7].
|Figure 6: (a) The cross-sectional images showed depression of the lingual cortex below the premolar region without any connection with apex of premolars. (b) cone beam computed tomography axial images revealed that the cavity located on the anterior region of the mandible with mental foramen relationship|
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|Figure 7: Three-dimensional cone beam computed tomography volume rendering reconstructed images revealed a bone defect at the anterior mandible|
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Successively, to learn the content of the cavity since this location is not as common as a posterior variant of SBC, MRI was performed. In the T1 fat-saturated, T2 fat saturated, and T1 fat saturated contrasted MRI images, the bone cavity is filled with soft tissue that is, continuous and identical in signal with that of the mylohyoid muscle. This is clearly seen in all types of sequences in various plains in [Figure 8].
|Figure 8: (a) Sag T1 FSE, (b) coronal short tau inversion recovery, (c) contrast COR T1 FSE (d) contrast axial T1 FSE, images shows that the mandibular defect is filled with tissue that is continuous and identical in signal with that of mylohyoid muscle|
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Final diagnose of the lesion was made as an anterior variant of SBC and the patient was informed about the lesion and recommended follow-up appointments for every 6 months.
| Discussion|| |
Stafne bone cavities are asymptomatic, ovoid-shaped, homogeneous, well-defined radiolucent lingual bone defects, which are usually detected incidentally on routine radiographic examinations.  There are variances in the location of SBC. The most common location of SBC is submandibular gland fossa close to the inferior border of the mandible, beneath the inferior dental canal, which is termed posterior variant of SBC. In our first case, SBC is located at the posterior mandibular region close to the inferior border of the mandible. The lingual anterior variant of SBC is 7 times less frequent than the posterior variant, which is located near the apical region of the premolars, associated with the sublingual glands such as our second case. Lingual and especially buccal bone cavities of ascending ramus are very rare findings such as in our previously reported case. ,
Several hypotheses have been offered for the etiology of SBC, and the cause is still controversial. According to Stafne,  bone cavities are developmental failures in the ossification process in the region that is occupied by cartilage. Philipsen et al.  declared that hyperplastic or hypertrophic salivary glands pressure on the bone surface can cause the formation of SBCs. Minowa et al.  hypothesized that SBC is the result of erosion caused by an acquired vascular lesion or lipoma.
Stafne bone defects (SBDs) can include generally salivary glands in accordance with their placement but can also include fat, connective tissue, lymphoid tissue, muscle and blood vessels and even SBCs can be empty.  Shimizu et al.  reported that SBDs which have a connection with the base of the mandible generally include soft tissues. In accordance with Shimizu et al.,  our first case, the posterior part of the bone cavity was filled with submandibular gland, but anterior part of the cavity was filled with proteinaceous content. No fatty content was detected. In the literature, anterior SBCs commonly contained normal or inflamed salivary sublingual salivary gland tissue.  In our second case, the content of the cavity was mylohyoid muscle, which is a rare finding in the literature.
Generally, no surgical treatment is necessary for SBCs, which are anatomic rather than pathologic. Clinical and radiographical examinations are adequate to confirm the static nature of cavities. , Surgical management and biopsy can be performed when the diagnosis is unclear , or to reduce the risk of the fractures when the defect has a critical size or has an alteration in size during the follow-up periods. , Prechtl et al.  presented a SBC case with significant enlargement during 17 years period. Kao et al.  presented a mandibular fracture related to Stafne bone defect. Consequently, imaging techniques and follow-up radiographs are important to diagnose these cavities. Panoramic radiographs may ensure knowledge concerning the diagnosis of SBC. Since CBCT provides examination the suspicious radiolucent lesions in all sections with lower radiation exposure and higher speed, it might be used for diagnosis of SBC cases instead of CT imaging.  Moreover, to identify the contents of the cavity, MRI with superior soft tissue characterization and differentiation and without ionizing radiation should be preferred. 
| Conclusion|| |
Differential diagnose of SBCs from other possible pathologies that may require treatment and imaging technique selection according to case is significant. CBCT and MRI might be serious for a definitive diagnosis. Moreover, especially in cases with critical size to monitor the alterations in size to reduce the risk of fractures follow-ups are very important and the patients should be informed and warned about the condition.
| Acknowledgments|| |
This case report reported on in a poster presentation at The European Society of Head and Neck Radiology (ESHNR) Congress, İzmir, Turkey, October 03-05, 2013.
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