|Year : 2019 | Volume
| Issue : 1 | Page : 40-44
Prevalence of Stafne's Cyst – A retrospective analysis of 18,040 Orthopantomographs in Western India
Sugandha Arya1, Ashish Pilania2, Jitender Kumar3
1 Department of Oral Medicine and Radiology, Vyas Dental College and Hospital, Jodhpur, Rajasthan, India
2 Department of Oral and Maxillofacial Surgeon, Sardana Hospital and Trauma Centre, Panipat, India
3 Department of Oral and Maxillofacial Surgery, SGT University, Gurugram, Haryana, India
|Date of Submission||14-Nov-2018|
|Date of Acceptance||01-Feb-2019|
|Date of Web Publication||23-Apr-2019|
Dr. Sugandha Arya
Vyas Dental College and Hospital, Jodhpur - 342 001, Rajasthan
Source of Support: None, Conflict of Interest: None
| Abstract|| |
Introduction: Stafne's cyst (SC) is a bone depression found on the lingual side of the mandible. It is a sharply demarcated osteolytic lesion of the mandible, caudal to the inferior alveolar nerve and restricted to the regions of the molars and mandibular angle. Purpose: Stafne's bone cyst is usually asymptomatic being diagnosed on the routine radiographs as an incidental finding hence, its actual prevalence is unknown. Moreover, the lesion simulates many odonogenic pathologies thereby, and the entity remains a diagnostic challenge. So, the present study was conducted to investigate the prevalence of SC in Jodhpur population of Western India. Materials and Methods: A retrospective analysis of 18040 OPGs was done on the basis of diagnostic criteria described by Stafne. Results: A total of 6 cases fulfilled diagnostic criteria of SC (0.03%), 4 cases were reported in men (66.6%), at a mean age of 50.75 years, and 2 cases in women (33.3%), at a mean age of 31.5 years. Involvement of SC on left and right side of the mandible was given as 4:2 in ratio. All 6 cases of SC was found in the body of mandible (100%). Rare case of double unilateral form of SC was reported in 1 patient. Conclusion: Orthopantomographs (OPGs) may ensure initial opinion regarding the diagnosis of SC and alert the clinicians to exclude other potential pathologies to avoid invasive procedures.
Keywords: Bone cavities, developmental defect, orthopantomographs, Stafne's bone cyst
|How to cite this article:|
Arya S, Pilania A, Kumar J. Prevalence of Stafne's Cyst – A retrospective analysis of 18,040 Orthopantomographs in Western India. J Indian Acad Oral Med Radiol 2019;31:40-4
|How to cite this URL:|
Arya S, Pilania A, Kumar J. Prevalence of Stafne's Cyst – A retrospective analysis of 18,040 Orthopantomographs in Western India. J Indian Acad Oral Med Radiol [serial online] 2019 [cited 2019 Aug 21];31:40-4. Available from: http://www.jiaomr.in/text.asp?2019/31/1/40/256896
| Introduction|| |
Edward C Stafne in 1942 described Stafne's cyst (SC) as bony cavities or defects occurring in the posterior mandible of 35 patients. These entities are asymptomatic and appear mostly unilaterallyas elliptical-shaped unilocular radiolucencies located in the lingual mandibular surface, below the inferior alveolar canal, between the first molar and the angle of the mandible.,, The size of the bony defects varies between 0.5 cm and 2.0 cm in diameter, and it rarely changes hence, SC are considered to be static lesions.
The exact pathogenesis of SC is obscure. Stafne suggested that the bony cavities might have resulted from a failure of normal bone deposition in the region formerly occupied by cartilage. Some authors suggested that it appeared because of entrapment of a part of the salivary gland during the development of the mandible.,, Pressure resorption theory stated that localized pressure of sublingual or submandibular gland to the lingual surface of mandibular bone induced the development of the defect and atrophy in that area. This theory was accepted because of the inadequacy of the congenital theory, which could not explain why the lesions do not occur in childhood,, Due to multiple explanations provided for its occurrence various synonyms like lingual mandibular bone defect, lingual mandibular bone depression, developmental submandibular gland defect of the mandible, Stafne lacune, Latent/Static/Idiopathic bone cyst, cavity or defect are jotted for this rare entity. It is also referred as the Non-neoplastic bony lesion. and because of the absence of a cystic epithelial lining it is considered as Pseudo cyst.,
The SC is a rare asymptomatic entity. It is usually reported as an incidental finding in radio graphs so regional variability exists in its reported prevalence. Hence, retrospective radiographic study was conducted on 18040 OPGs to estimate the true prevalence of SCs in Jodhpur population of Western India.
| Materials and Methods|| |
A retrospective radiographic study was done fora period of 1 year (2016–2017) in the Department of Oral medicine and Radiology at Vyas dental college and Hospital, Jodhpur. In this study after obtaining consent from the patients, a retrospective evaluation of a large patient population data consisting of 18040 OPGs was done. All Ortho pantomogram (OPG views) had been performed and archived on the same radiological device (Kodak 8000 C operated at 8-12 mA, peak voltage ranging from 70-80 Kvp. All OPGs views were screened and evaluated by the first author to estimate the prevalence of Stafne's cyst. Evaluation of SC was done on the basis of the diagnostic criteria that described “SC as a sharply demarcated osteolytic lesion of the mandible caudal to the inferior alveolar nerve and restricted to the regions of the molars and mandibular angle.”,
The ethical clearance for the conduct of this research was obtained and no conflicts of interest had been reported in our study.
| Results|| |
Amongst the 18040 screened OPG views of patients, a total of six fulfilled the diagnostic criteriaof Stafney's cyst hence, reporting a prevalence of 0.03% in Jodhpur population of Western India [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6]. On radiographs, SC appeared as a well-defined unilocular radiolucency surrounded with a thick corticated border and was located in the lingual mandibular surface, below the inferior alveolar canal, between the first molar and the angle of the mandible. In this study OPG radiographic views were sufficient to verify the diagnosis of SC without the requirement of 3 dimensional staging. On screening, ratio of SC affectingthe male and female gender group was observed to be m/f (2:1). Four cases (66.6%) of SC were reported in men with a mean age of 50.75 years, and two cases (33.3%) of SC were reported in females with a mean age of 31.5 years. The most prevalent location of SC was observed in the body of mandible for all six cases (100%). Left side (66.6%; 4 cases) [Figure 2], [Figure 4], and [Figure 5] of the mandible was more commonly affected by SC than the right.(33.3%;2 cases) [Figure 1] and [Figure 3]. The round form of SC was observed in two OPG views [Figure 3] and [Figure 6], and remaining four were found with an oval form. The sizes of all six diagnosed SC cases ranged from 0.7–3 cm in diameter. The unilateral occurrence of SC was reported in all six cases (100%). Five cases of SC (83.3%) occurredas a solitary defect and one double unilateral form of SC (round and oval shape) was observed on left side of the mandible [Figure 6].
|Figure 1: OPG of a 35 year-old female showingStafne's cyst in the right body of mandible, with an oval form|
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|Figure 2: OPG of a 38-year-old male showingStafne's cyst in the left body of mandible, with an oval form|
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|Figure 3: OPG of a 42 year-old male showingStafne's cyst in the right body of mandible, with a round form|
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|Figure 4: OPG of a 55-year-old male showingStafne's cyst in the left body of mandible, with an oval form|
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|Figure 5: OPG of a 68-year-old male showing Stafne's cystin the left body of mandible, with an oval form|
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|Figure 6: OPG of a 28-year-old female with Double unilateral appearance of Stafne's cyst in the left body of mandible, with an oval form and a round form|
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| Discussion|| |
Stafne's bone cavity of the mandible is a rare destructive bone lesion. It is highly localized, non-progressive and doesnot heal. It is usually detected in routine maxillofacial radiology as an incidental finding. The classic Stafne defect presents as an asymptomatic radiolucency below the mandibular canal in the posterior mandible, between the molar teeth and the mandibular angle. The lesion is typically well circumscribed with a sclerotic border.,,,,
Prevalence of the SCranges from 0.10% to 0.48%, with a male-to-female ratio of 4 to 1 which is in contrast to our study wherein 0.03% prevalence of SC had been reported in six cases amongst 18040 OPGs. Other authors; Karmiol M and Walsh RF (1968) reported 18 SC cases amongst 4963 and predicted a prevalence of 0.3%.,, Oikarinen VJ and Julku M found 10 cases in a survey of 10000 OPG and depicted a frequency of 0.1%. Correl RW et al. discovered 13 cases in 2693 OPG and revealed a prevalence of 0.48%. However, some cadaver studies concluded that the incidence of the lesion may increase up to 6.06%.,, This difference could be due to asymptomatic characteristic of the lesion.
The SC occurs most frequently in middle-aged and older men in fifth and sixth decades of life with an incidence of 4:1000 adults., Philipsen et al. in their comprehensive study, showed a 6:1 male/female ratio for SC which was in contrast to our study where 2:1 male/female ratio had been observed. Majority of the cases reported in our study were in second and sixth decades which could be explained as SC being asymptomatic and is incidentally diagnosed on radiograph. In our study, four cases (66.6%) were diagnosed in men (66.6%), which was in accordance to the study reported by Gomez et al. who reported 11 cases of SC in whom 8 were men. Correl RW et al. reported96% prevalence in men hence, verifying the male dominance of this entity. In a study reported by Alexandre et al. all 11 casesof SC were observed in men (100%), at a mean age of 58.1 years which was in accordance to our study wherein four out of six cases were reported in men (66.6%), at a mean age of 50.75 years and two cases in women (33.3%) at a mean age of 31.5 years.
On OPGs, SC typically exhibit cystic signs, such as a round or oval, radiolucent lesion, mostly affecting distal areas of the mandibular corpus or the angle, located under the inferior alveolar canal., In our study, all six cases were observed in the body of mandible (100%). In our study, round form of SC was observed in two OPG views [Figure 3] and [Figure 6] and remaining four were found with an oval form. The scientific literature has stated four types of SC - posterior lingual, anterior lingual, buccal aspect of ascending ramus and lingual aspect of ascending ramus. This abnormality if observed in an anterior lingual location, between the incisor and the premolar areas, above the insertion of the mylohyoid muscle it is called as anterior lingual bone defect. In our study all 6 cases (100%) were of posterior lingual type of SC. Thereby, verifying posterior lingual location of SC being seven times more frequent than the anterior lingual one and can be readily diagnosed because of its unique location in the radiographic examination.,,
Radiographically, the cavity appears as an elliptical, oval or round homogeneous well-defined unilocular radiolucency, often with a sclerotic margin, and between 1 to 3 centimeter in size, located in the first molar to angle area below the mylohyoid line and the inferior alveolar canal and above inferior border of mandible. A peripheral rim of sclerosis may be seen, which is usually thicker on the superior border as compare to odontogenic cysts because of the x-rays passing tangentially through the wall of the pseudocystic depression. All these features were present in all four cases reported in our study except that the size of SC varied from 0.7 cm to 3cm.
SC is found to be mostly unilateral. Bilateral occurrence has been reported in very few studies. Double unilateral occurrence of SCis rare, and bilocular occurrence is even rarer.,,, In our study all five cases of SC were observed unilaterally but onerare double unilateral form of SC is reported in our study [Figure 6]. According to a study reported by Alexandre et al., eight patients (72.7%) had SC on the left side, three patients on the right side (27.3%) which is in contrast to our study whereinleft side (66.6%; 4 cases) [Figure 2], [Figure 4], and [Figure 5] of the mandible was more commonly affected by SC than the right.(33.3%; 2 cases) [Figure 1] and [Figure 3].
A key anatomic feature of Stafne bone defect is that the mandibular concavity always is open on its lingual face and the mandibular bone cortical is not compromised which is appreciated with CT scan as the focal defect at the lingual cortex which is continuous with adjacent soft tissues., To confirm direct herniation of the submandibular gland into the defect, MR imaging is the preferred technique thereby, supporting the developmental origin of the lesion. Intraoral dental films or OPGs, although sufficient for diagnosis, may not be definitive in atypical lesions (e.g., incompletely corticated, lobulated, multiple, or in an uncharacteristic location), demanding a need for 3D imaging. Confirmatory testing is warranted in these situations, as the differential diagnosis for mandibular radiolucencies includes periapical cyst, traumatic bone cyst, odontogenic keratocyst, dentigerous cyst, fibrous dysplasia, ameloblastoma, focal osteoporotic bone marrow defect etc. The clue to the correct diagnosis is the characteristic appearance and location of SC at the mandibular angle below the inferior alveolar nerve canal where as odontogenic cysts (periapical cyst, dentigerous cyst), and odontogenic tumors (ameloblastoma) are always present above the inferior alveolar canal. Other cysts like traumatic bone cyst which is also a pseudo cyst like SC but is located above the inferior alveolar canal with its borders running in between the roots of the tooth giving a scalloped appearance. Fibro-osseous lesion like fibrous dysplasia mostly causes unilateral facial asymmetry and is common in maxilla but if occurs in mandible, causes superior displacement of mandibular canal. Another differential diagnosis of SCcould be focal osteoporotic bone marrow defect which is usually seen as a radiolucency with distinct or ill-defined margins in middle-aged woman and is located in the posterior aspect of body of mandible., Cross-sectional imaging is found to be effective in confirming the diagnosis of SC by demonstrating submandibular glandular tissue within the defect. Recently, sialography of the submandibular gland is performed by injecting a radiopaque dye into the Wharton's duct which is useful to differentiate a SC from other lesions, If the dye gets carried through the radiolucency, the diagnosis of Stafne bone cavity is confirmed. Histologically, the Stafne bony defect may contain salivary gland, lymphoid tissue, fat, connective tissue, muscle or blood vessels. Empty cavities have also been reported., SC are mostly asymptomatic, if they are associated with symptoms like pain and paresthesia, a biopsy or surgical exploration may be required to rule out other pathological condition like a neoplastic pathology (e.g., pleomorphic adenoma) or chronic sialadenitis. Although Stafne bone defects are considered static lesions which are basically diagnosed on routine radiological examinations. Since patients do not usually present clinical signs thereby, out of two main therapeutic options documented- surgical intervention or a 'wait and see' approach, the latter is being preferred, always with periodic clinical and radiological controls.
| Conclusion|| |
Stafne's cyst is a rare aymptomatic entity which is usually detected in routine maxillofacial radiology as an incidental finding. Actual prevalence of the defect remains unknown. This retrospective radiographic study was conducted in Vyas dental college, Jodhpur to estimate prevalence of SC in a large patient population data consisting of 18040 OPGs. Results revealed that SC was observed in 6 cases amongst 18040 screened viewshence, prevalence of SC was reported to be 0.03%. Diagnosis of SC is essential because of its similarity with other odontogenic pathologies. Ortho pantomographs (OPGs) may ensure initial opinion regarding the diagnosis of SC and alert the clinicians to exclude other potential pathologies to avoid invasive procedures.
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Conflicts of interest
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6]