Journal of Oral Disease Markers (2019), 3, 33–35

Case Report

Stafne bone cavity: A rare case affecting the anterior Annie Pellatt1, Michelle Wooi2, Peter Revington1

1Department of Oral and Maxillofacial Surgery, University of Bristol Dental Hospital, Bristol, United Kingdom, 2Dental Core Trainee, University of Bristol Dental Hospital, Bristol, United Kingdom

Keywords: Abstract Anterior, , mandible, Stafne Stafne bone cavity (SBC) is a well-documented with clear radiographic diagnostic parameters. Usually occurring in the posterior mandible, the lesion contains salivary Correspondence: Michelle Wooi, Department of Oral and gland tissue and is asymptomatic and non-invasive. In contrast, anterior salivary gland Maxillofacial Surgery, University of Bristol inclusion defects are rare and can present a diagnostic conundrum. They can be unilateral Dental Hospital, Bristol, United Kingdom. or bilateral and may appear anywhere between the premolar teeth. The anterior variant E-mail: [email protected] is commonly confused with radicular and radiographically can be similar to other insidious . This report provides a rare example of a bilobed anterior salivary gland Received: 23 June 2020 inclusion cavity in a 21-year-old male. We have provided diagnostic recommendations Accepted: 17 July 2020 based on this case, and others reported in recent literature. doi: 10.15713/ins.jodm.26

Introduction The apical of odontogenic origin was ruled out with periapical radiographs and pulp sensibility testing. The lesion Stafne bone cavities (SBCs) are pseudocysts of the mandible. was asymptomatic, and due to 3-pack year history of smoking, First defined by Stafne in 1942, they are depressions of the lingual the lesion was treated as suspicious, and the patient urgently cortical bone of the mandible, containing ectopic salivary gland [1] referred. There was no other relevant medical history. tissue. They appear radiographically as uniloculated, well- A cone-beam computed tomography (CBCT) of the defined radiolucencies below the inferior alveolar nerve (IAN) [1] mandible demonstrated a partially multilocular defect extending canal in the third molar region. SBCs have an incidence of 0.1– from the lower right second premolar, crossing the midline 0.48%, most commonly occurring in men in the fifth and sixth [2,3] into the lower left second premolar, and enveloping the apices decades. Similar lesions have been identified on the ascending of most of the anterior teeth [Figure 2a and b]. The buccal ramus and also lingually in the anterior mandible, although the [4,5] plate was, in most part, intact, but there was lingual expansion incidence of these variants is less. SBCs are asymptomatic and thinning of the lingual plate [Figure 2c]. The lesion had a and are usually noted as serendipitous findings during routine radiographic appearance of giant cell granuloma, keratocyst, dental checks. This case report presents a rare case of a bilobed ameloblastoma, or sialodontogenic tumor. Thus, a of the anterior variant of SBC, even more unusual that it occurs in a lesion was performed, where it was evident salivary gland tissue young patient. In reporting this case, we hope to highlight the occupied the lesion. Microscopy confirmed mucous type salivary key diagnostic principles and features of this rare lesion. gland tissue favoring that of the . In conjunction with CT and biopsy, a magnetic resonance Case Report imaging (MRI) floor of the mouth was performed showing a well-defined bilobed soft-tissue mass lying anteriorly on the floor A 21-year-old male was referred to the Bristol Maxillofacial unit of the mouth [Figure 3]. The MRI concluded that the lesion following an incidental finding of a bilateral unilocular lesion in represented an anterior variant of a Stafne cyst. the anterior mandible at a dental check-up. The lesion, which The patient was followed up and MRI repeated for extended from the lower right premolars to the left premolars, comparison at 6 months and 1 year. The lesion had not changed was identified on a dental panoramic radiographFigure [ 1]. in size and the patient remained asymptomatic.

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Discussion odontogenic keratocysts, and salivary gland tumors. Therefore, it is recommended that a biopsy is taken for an accurate diagnosis Pathogenesis of the anterior SBC. Stafne defects are generally considered to be a congenital anomaly. During mandibular development, part of the salivary gland tissue becomes trapped in the developing mandible. This is consistent with the clinical sign of perforation in the lingual cortex with continuity of the lesion to the adjacent salivary gland. An alternative theory suggests that over time pressure from adjacent soft-tissue structures – such as salivary glands, facial artery, or lymphatic infiltration – may lead to the development of these bony defects.[6,7]

Incidence Figure 1: Dental panoramic tomography of the patient which The anterior variant of the Stafne bone cavity can be more demonstrates a large area of radiolucency in the mandible from accurately referred to as a lingual mandibular salivary gland lower left second premolar to lower right second premolar. defect, inclusion, or depression. First reported by Richard and Ziskind in 1957, there have been infrequent reports of this anomaly since.[8] A review of the current literature would suggest that there have been fewer than 60 cases reported since this date.[6,7] The majority of reports of anterior SBC have described lesions between the canine and lower first molar.[9] The presented case is unusual in that the lesion is bilateral and superimposed over the anterior teeth up to the second premolars on either side. A similar case of bilateral anterior mandibular SBC was reported a b in 2014.[7] Like the posterior variant, anterior SBCs usually occur in males in the fifth or sixth decade. Interestingly, we present a case in a 21-year-old man – the youngest reported case to date.

Diagnosis The anterior variant of SBC can prove to be diagnostically problematic. Unlike its posterior equivalent, the anterior SBC does not have established radiographic defining characteristics. c The posterior SBC is almost always at the angle of the mandible [1] Figure 2: Computed tomography images reflecting the lesion below the IAN and radiographically can be seen as unilocular. occupying the anterior mandible (a). The buccal plate was mostly These clear parameters mean SBCs can be confidently diagnosed intact, but there is thinning of the lingual plate (b and c) from clinical and radiographic examination alone. In contrast, anterior SBCs can be unilocular or multilocular, occur anywhere in the anterior mandible, and can be superimposed over the roots of anterior teeth. They are more often unilateral, but occasionally present as a bilateral lesion. These inconsistent features and rarity of the lesion make diagnosis challenging. A biopsy is needed in conjunction with imaging studies to confirm the diagnosis.

Management Most commonly, they are misdiagnosed as radicular cysts, and it is therefore important to exclude dental pathology by carrying out pulp viability tests, such that no unnecessary a b [6] endodontic treatment is carried out. The anterior variants Figure 3: Magnetic resonance imaging images showing a reasonably can also bare resemblance to several other symmetrical bilobed, well-defined soft-tissue mass lying anteriorly radiographically. Differential diagnoses include fibro-osseous in the sublingual space (a and b). It is associated with scalloped lesions, ameloblastoma, myxoma, central giant cell lesions, bone loss affecting the lingual aspect of the body of the mandible

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Conclusion mandibular bone concavity: Report of case. J Oral Surg 1981;39:599-600. Anterior variations of SBCs are rare, with less than 60 cases 3. Ström C, Fjellström CA. An unusual case of lingual mandibular reported in the literature since Stafne first described the anomaly depression. Oral Surg Oral Med Oral Pathol 1987;64:159-61. in 1942. The lesion is asymptomatic and is not pathogenic per se, 4. Murdoch-Kinch CA. Developmental disturbances of the face but rather considered an anatomical variant. The anterior SBC and jaws. In: White SC, Pharoah MJ, editors. 6th ed. Oral is uncommon and poses a diagnostic quandary to those who Radiology: Principles and Interpretation. Saint Loius, MO: come across it – usually by chance in routine dental radiographic Mosby; 2009. p. 562-77. examinations. Commonly, it is confused with a radicular cyst but 5. Campos PS, Panella J, Crusoe-Rebello IM, Azevedo RA, Pena N, Cunha T. Mandibular ramus-related stafne’s bone cavity. radiographically can mimic other more sinister pathologies. Dentomaxillofac Radiol 2004;33:63-6. 6. Turkoglu K, Orhan K. Stafne bone cavity in the anterior Recommendations mandible. J Craniofac Surg 2010;21:1769-975. 7. Kim H, Seok JY, Lee S, An J, Kim NR, Chung DH, et al. Bilateral It is recommended that initial plain film imaging is corroborated stafne bone cavity in the anterior mandible with heterotopic with a CT scan of the mandible. Further imaging using MRI salivary gland tissue: A case report. Korean J Pathol 2014;48:248-9. can identify the nature of the contents of the bony cavity, but 8. Richard EL, Ziskin J. Aberrant salivary gland tissue in mandible. we recommend clinical biopsy and histopathological analysis to Oral Surg Oral Med Oral Pathol 1957;10:1086-90. validate the imaging studies.[10,11] The significance of accurate 9. de Courten A, Küffer R, Samson J, Lombardi T. Anterior lingual mandibular salivary gland defect (stafne defect) presenting as diagnosis is to rule out destructive disease and thus prevent a residual cyst. Oral Surg Oral Med Oral Pathol Oral Radiol unnecessary invasive treatments. A key feature of SBCs is that Endod 2002;94:460-4. they are unlikely to expand or become locally destructive, 10. Katz J, Chaushu G, Rotstein I. Stafne’s bone cavity in the anterior and therefore follow-up MRI studies are indicated to confirm mandible: A possible diagnostic challenge. J Endod 2001;27:304-7. quiescence. 11. Krafft T, Eggert J, Karl M. A stafne bone defect in the anterior mandible-a diagnostic dilemma. Quintessence Int 2010;41:391-3. References How to cite this article: Pellatt A, Wooi M, Revington P. Stafne 1. Stafne EC. Bone cavities situated near the angle of the mandible. bone cavity: A rare case affecting the anterior mandible. J Oral J Am Dent Assoc 1942;29:1969-72. 2. Layne EL, Morgan AF, Morton TH Jr. Anterior lingual Dis Markers 2019;3(1):33-35.

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