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Case Report
Is cone-beam computed tomography diagnostic for anterior Stafne bone cyst: Report of a rare case Abbas Shokri, Maryam Baharvand1, Hamed Mortazavi1 Department of Oral and Maxillofacial Radiology, Dental School, Hamadan University of Medical Sciences, Hamadan, 1Department of Oral and Maxillofacial Medicine, Dental School, Shahid Beheshti University of Medical Sciences, Tehran, Iran
A B S T R A C T Introduction: The incidence of anterior Stafne bone cyst (lingual mandibular bone defect, static bone cyst, latent bone cyst, developmental submandibular gland defect of the mandible) has been estimated to between 0.009% and 0.3%. It is characterized by a round or ovoid, well-defined border, unilocular radiolucency. Most of anterior Stafne bone defects were located between the cuspid and the first molar, but a few cases have been reported in the incisor area. Case Report: We present a 48-year-old man with anterior Stafne bone defect in the incisor area diagnosed by using cone-beam computed tomography (CBCT). Discussion: CBCT can be a confirmatory imaging technique to detect anterior mandibular bony configurations such as Stafne bone cavity with the lingual cortical plate being spared. Key words: Cone-beam computed tomography, jaw cyst, mandible
Introduction Stafne bone defect (SBD) was first described in 1942 by Stafne.[1] It is characterized by a round or ovoid, welldefined border, unilocular radiolucency, which is located below the mandibular canal, between the first molar and angle of the mandible.[2] Presence of this entity in the anterior region of mandible is rare. Richard and Ziskind reported the first case of SBD in the anterior mandible in 1957.[3] The incidence of this variant has been estimated to be between 0.009% and 0.3% with a male predilection (about 70% of all cases).[2,4] Most of the reported anterior Stafne bone defects (ASBDs) were located between the cuspid and the first molar (65%). A few cases have been reported in the incisor area, while the remaining (11%) Access this article online Quick Response Code: Website: www.dentalhypotheses.com DOI: 10.4103/2155-8213.150872
included more extensive lesions spreading through the anterior mandible.[4] Because ASBD is extremely rare, the diagnosis is a matter of challenge and sometimes might be missed or misdiagnosed as other unilocular radiolucencies, such as radicular cyst, residual cyst, odontogenic keratocyst, lateral periodontal cyst, etc.[2,5] Review of literature showed a few number of ASBD case reports during recent 60 years, after this lesion was first described. On the other hand, cone-beam computed tomography (CBCT) has been suggested to detect suspicious jaw lesions especially those located in the anterior region, because plain radiography is not applicable for this region.[2,4] The aim of this paper was to present a new case of ASBD in an Iranian patient for the first time, which was diagnosed by means of CBCT.
Case Report A 48-year-old man was referred to our clinic for CBCT examination before prosthodontic treatment. In the panoramic view of CBCT, a radiolucent lesion with welldefined border was noticed in the left incisor region
Corresponding Author: Prof. Hamed Mortazavi, Department of Oral and Maxillofacial Medicine, Dental School, Shahid Beheshti University of Medical Sciences, Daneshjoo Blvd, Tabnak St, Chamran Highway, Tehran - 1983963113, Iran. E-mail:
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of the mandible below the root of the extracted lateral incisor [Figure 1]. The patient’s medical history was unremarkable, and he did not have a history of trauma to that region. In addition, he had not undergone any jaw surgery. The overlying mucosa of the defect was normal with no evidence of infection or sinus tract. The lesion was unilateral, unilocular, and of 5 mm × 6 mm × 3 mm size. The shape and location of the lesion revealed a residual cyst as a tentative diagnosis at the incisor region of the edentulous mandible. The lesion was asymptomatic, and there was no history or sign of expansion as well.
Figure 1: Panoramic-like view shows the lesion in the anterior mandible
Cross-sectional and three-dimensional view of the lesion showed a lingual bony defect at the left incisor region of the mandible with the lingual cortical plate being spared [Figures 2 and 3]. According to the radiographic features, the lesion was diagnosed as an anterior variant of a SBD. Finally, the patient was advised about the lesion and scheduled for follow-up.
Discussion The pathogenesis of SBD is not fully understood. Although most authors believe it has a congenital origin, others consider it as a developmental entity.[5] Stafne suggested that it could be related to a congenital defect due to entrapment of a glandular tissue portion during mandibular development.[1] According to this, the submandibular salivary gland is responsible for development of posterior SBD, whereas entrapment of sublingual salivary gland causes ASBD.[5,6] In this paper, we reported a 48-year-old male with asymptomatic, unilocular anterior Stafne bone cavity in the mandibular central and lateral incisor area. In accordance to our case, it is demonstrated that men are more affected than women with male to female ratio of 3:1.[2] In addition, it is reported that the age of patients with ASBD ranged from 18 to 64 years with the mean of 43 years.[4] According to Turkoğlu, the highest incidence of ASBD for men was in the fifth and sixth decades similar to our case.[2] In agreement with our report, de Courten, demonstrated that most of cases are asymptomatic and diagnosed in routine radiographic assessments.[4] In contrast, few cases were reported with pain by Bornstein and Apruzzese.[7,8] Anterior variant of SBDs are usually found between or below the roots, superimposed over the roots, or at previous sites of tooth extraction like our case.[4] Sisman concluded that 17% of all cases seen in edentulous regions.[5] Review of literature showed that only 24-26% of cases involved the incisor area, whereas 57-65% were located between the cuspid and the first molar.[2,4] The size of cavities is ranged from 0.5 cm to 2 cm[2], but some cases with progressive and larger sizes have been reported 32
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Figure 2: Axial serial sections show intact mandibular lingual cortical plate
a
b
Figure 3: (a and b) Three-dimensional axial and lateral views of the defect with spared mandibular lingual cortical plate
as well.[9] The size of cavity in our case was 5 mm × 6 mm × 3 mm. Radiographically, the bone defects usually appeared as circumscribed, unilocular radiolucencies as in our case[2], but Etöz reported a multilocular lesion in one case.[10] Occasionally, the borders were sclerotic; while in other cases, they were not clearly defined.[1,4] Sometimes, the tissue was enclosed by bone, but in most of them a softtissue invagination into the lingual cortical plate is noted above the level of mylohyoid insertion.[2,6,7] Because ASBDs are considered as anatomic defects rather than pathologic lesions, non-invasive diagnostic radiography with the aid of different techniques, such as computed tomography (CT), CBCT, sialography, and magnetic resonance imaging (MRI), and appropriate clinical follow-up is suggested rather than surgical intervention or biopsy.[2,4,6] Most case reports of Stafne bone cavities have addressed the Jan-Mar 2015 / Vol 6 | Issue 1
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findings on intraoral dental films, plain films of the mandible, or panoramic view of jaws. However, these imaging techniques may not be definitive when the lesion is atypical (e.g., lobulated, incompletely corticated, multiple, or in an unusual location). In these situations, complementary imaging is warranted. Sialography has been used to confirm the diagnosis by depicting salivary ducts within the bony defect, but there are case reports of surgically proved Stafne bone cavities with negative sialograms. Sialography can be difficult to perform and uncomfortable for the patient, and it exposes the patient to ionizing radiation.[11] Contrary to the posterior SBD, conventional sialography of sublingual gland presents a limited value for diagnosis of ASBD, because cannulation of the Rivini is extremely difficult and not recommended. Meanwhile, other complications such as high failure rate, duct trauma, acinar rupture, and possible sepsis have limited its overall use.[2] Münevveroğlu has reported application of CBCT and CT in detection of ASBD.[12] In most CT evaluations of Stafne bone cavities, salivary tissue is evident within the defect, but small Stafne bone cavities may contain only fat or soft tissue due to regression of the gland or intermittent herniation. CT has the disadvantages of radiation exposure and possible contrast reactions. That is why some authors advocate MRI as the primary confirmatory technique.[11] Sisman showed that there is no difference between multislice CT (MSCT) and CBCT in detection of ASBD. The CBCT could be suggested as the most suitable noninvasive diagnostic modality for this bony configuration of the mandible, since it provides a lower radiation exposure dose than that of MSCT.[13] MRI can show the soft tissue containing mandibular defect as well. If an adequate quantity of saliva is present, clear visualization of these tissues is obtained with a 1.0-mm slice thickness.[2] MRI has the benefit of multiple imaging planes and different echo sequences, but it is expensive and causes field distortion artifacts from dental material. The diagnosis of Stafne bone cavity may be established with a limited MR examination, which shows the mandibular defect containing soft tissue continuous and isointense with the submandibular gland on both proton density and T1-weighted sequences.[11] In addition, Kopp has introduced a new technique named Digital Volume Tomography (DVT) to detect SBD. The additional use of DVT 3D examination may help in diagnosis of Stafne Idiopathic Bone Cyst (SIBC) prior to surgical interventions, thus avoiding unwanted surgical intervention.[14] Jan-Mar 2015 / Vol 6 | Issue 1
Both posterior and anterior variants of SBD need no treatment. Surgical exploration and biopsy should be considered only to rule out other pathologic entities in unusual cases. Moreover, when the diagnosis is uncertain or exceptionally when an additional pathology is suspected to develop in the entrapped salivary tissue diagnostic surgery might be indicated.[4,6] In conclusion, CBCT can be a confirmatory imaging technique to detect anterior mandibular bony configurations such as Stafne bone cavity with the lingual cortical plate being spared.
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Cite this article as: Shokri A, Baharvand M, Mortazavi H. Is cone-beam computed tomography diagnostic for anterior Stafne bone cyst: Report of a rare case. Dent Hypotheses 2015;6:31-3. Source of Support: Nil, Conflict of Interest: None declared.
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