Benign Mandibular Cavity/Stafne’s Bone cyst: A case report and reviewClinical MessageStafne’s Bone Defect is discovered incidentally on radiographic examination a radiolucent lesion in the body of the mandible, managed conservatively as it is asymptomatic. Its presentation can mimic a malignancy if symptomatic. Hence, it may raise a high index of suspicion unless a histopathological diagnosis rules it otherwise.IntroductionEctopic salivary gland tissue has been previously reported and described within various head and neck anatomical sites, including: the mastoid bone, middle ear, cervical lymph nodes, varied mandibular regions, and skin of the neck skin1. One unique case of ectopic salivary gland tissue is the Stafne bone defect (SBD)2.  In 1942, Edward Stafne described this defect as being an anatomic rather than pathologic condition, whose probable cause is soft tissue inclusion.  SBD is commonly found beneath the mandibular canal, between the first molar and angle of the mandible3. Diagnosed radiographically, they appear as circular, unilocular radiolucencies, giving way to other preferred diagnostic terms, such as: Stafne’s bone cyst/defect/cavity, mandibular salivary gland inclusion, ectopic/aberrant salivary gland, lingual mandibular bone cavity, static/idiopathic defects, or cavity3,4.   In most cases, Stafne bone defects (SBD) comprise ectopic glandular tissue.  However, muscle, lymphoid tissue, connective tissue, fat, soft tissue, or vasculature may be additionally found in the bone cavity2.Stafne’s bone cavities (SBC) remain a rare finding; therefore, most often present as an asymptomatic incidental discovery during routine dental checks.  SBCs have an incidence of 0.1% to 0.48%, affecting mostly males in the fifth to seventh decades 5.  Stafne defects have been previously reported to be a congenital anomaly.  It is postulated that during mandibular development, the partial entrapment of the salivary gland tissue in the developing mandible causes such defects 5 .  Authors state when the submandibular gland is under pressure, this defect could arise as an auxiliary effect.  It could also arise due to weakening or destruction via the adjoining lingual cortical plate 1.The aim of the current report is to describe a patient complaining of a painful lesion that led to the suspicion of an occult malignancy, yet, another unique presentation of a benign intramandibular salivary gland inclusion manifestation.Case History/ExaminationA 66-year-old otherwise healthy male patient presented with localized, dull pain on the left side of the jaw for about 3 months. There was no reported use of pain medications and his medical history was unremarkable. The patient reported smoking an average of 20 cigarettes daily and a glass of whiskey weekly for > 50 years. Upon examination, extra and intraoral examination was normal revealing no swelling on the left of the mandibular region. On deep palpation, the area apical to the left lower molar region elicited an area of tenderness, although the overlying mucosa was normal.Methods(Investigations, Differential diagnosis and treatment)The patient was sent for a Computed tomography (CT) orthopantomogram ( CT-OPG) and CT scans- axial cuts, and coronal cuts including 3D-Reformatted images. The axial cuts highlighted thinning of the mandibular cortex, whereas the 3D-reformatted images illustrated perforation of the buccal and lingual cortices inferior to the mandibular canal (Fig. 1A, Fig. 2A,2B). The CT scans revealed a left defined unilocular corticated lytic non-enhancing lesion that measured 22.6mm X 9.0mm X 13.4mm {anterior posterior(AP) X transverse(TR) X craniocaudal(CC) }, in the posterior aspect of the left mandible, adjacent to the angle of the mandible. The corticated lesion did not communicate with the mandibular canal and adjacent roots (Fig. 3A, B). The differential diagnosis included an occult metastatic malignancy, multiple myeloma, and SBC.Preoperative preparation included blood tests (full blood count and urea/electrolytes and creatinine), high resolution chest X-ray, liver function tests, and electrocardiocardiography, which were all normal. Under nasotracheal intubation, an incisional biopsy was obtained intra-orally from the tender ramal region of the mandible.ResultsHistopathological examination reported it as a benign intramandibular salivary gland inclusion. The macroscopic appearance was of multiple soft tissue 2cm in diameter and microscopically the tissue consisted mainly of salivary gland tissue with benign ducts, acini, and adipose tissue. Additionally, no features of cell atypia were observed (Fig.4). The recovery was uneventful, and the patient has been asymptomatic both, clinically and radiographically. The patient has been on review for the past eighteen months with no change in the current status of the lesion.DiscussionClinicians abide by the Hippocratic oath (primum non-nocere )6. Aggressive investigative approaches are ordinarily not adopted when the presentation is in keeping with all the radiological features of SBC. However, when a patient complains of dull pain, a biopsy is indicated as was the case in this patient. Among the list of differentials, it was pertinent to rule out the presence of an occult malignancy in keeping with a history of tobacco and alcohol consumption of >50 years. Radiological examination of the lesion gave it a classical description aligning with that of an SBC.The latter has been described as radiolucency dorsal to the mandible, inferior to the mandibular canal, above the cortical border of the mandible 7,8,9,10,11,12. Studies on the size of the bony defects have recorded values ranging from 0.5cm to 2.0cm with hardly any increases or decreases in dimension of the lesion assuming more of a static nature 13,14,15. In another study, volumetric measurements of SBC dimensions using Cone Beam CT showed ranges from 1 to 3 cm in diameter, depth (7,8mm), and width (16,3mm) respectively 16 . Although our patient had a CT scan, the lesion was reported to have a height of 13.4mm and width of 22.6mm, larger than the dimensions reported in the study by Adisen et al., 201517. There are two types of SBC, the anterior lingual variant (located amidst the incisors and the premolars, above the insertion of the mylohyoid insertion), the second is the posterior variant, which has been shown to be seven times more prevalent. The patient presented with the commoner posterior variant type18,19,20. SBC tends to present more in males than females (6:1 to 2:1) during the 4th to 6th decade of life with no racial bias. The age and gender of presentation in this patient was 66-year-old male of Indian origin 21,9,22.The etiology of SBC has been unclear with scanty histopathology evaluation of tissue. SBC has been a presumptive incidental radiological diagnosis due to its asymptomatic clinical presentation7,6. The precision of the term “SBC” during diagnosis, has been interrogated by many authors, preferring a change to “benign mandibular concavity”. Therefore, the possibilities are to presume that the erosion may have been caused by resorptive forces from a vessel, incomplete Meckle cartilage calcification during ossification or enlarged lobe of a salivary gland, or as was suspected in this patient, by an occult malignancy initially.In our patient, the tissue was intramandibular consisting of both salivary gland and adipose tissue with no cell atypia reported “benign mandibular concavities” are known to contain either salivary gland, lymphoid, muscular, adipose and vascular tissue. Our histopathological report was in keeping with two types of tissue found within the specimen: salivary and adipose tissue7,12,24,25,26,27,28,29,16,30,31,32,33,34,35,21,36,37,10.In general, these lesions are localized, non-progressive, non-healing, and are diagnosed as incidental findings with no clinical evidence. Therefore, often, a watch and wait approach is adopted with regular clinical and radio imaging 37.ConclusionIn this patient, surgical exploration followed by histopathology was pertinent due to the suspicious nature of the symptoms surrounding the SBC or “mandibular concavity” to rule the presence of an occult malignancy.Compliance was with Ethical StandardsConflicts of Interests: NoneAuthors Contribution: Dr Fawzia Butt Manuscript preparation and Submission & Miss Shamim Afrid Manuscript EditingConsent Form: I confirm I have obtained a written informed ans signed consent form from the patient and it has been uploaded as well.ReferencesPhero, J. A., Hannan, E., Padilla, R. & Turvey, T. Ectopic salivary tissue of the mandibular condyle: A case report and review of the literature. Oral and Maxillofacial Surgery Cases 6, (2020); Volume 6, Issue 3;100167, ISSN 2214-5419.Togni L, Mascitti M, Santarelli A, et al. Unusual Conditions Impairing Saliva Secretion: Developmental Anomalies of Salivary Glands. Front Physiol . (2019); 10:855. Published 2019 Jul 3. doi:10.3389/fphys.2019.00855.Sekerci, A.E., Sisman, Y., Etoz, M., Aksu, Y. Aberrant location of salivary gland inclusion: Report of a case with review of the literature. European Journal of Radiology Extra( 2011);79(1): e27-e31.Venkatesh A, Radder K, Harish K and Hegde V. Anterior Mandibular Lingual Salivary Gland Defect Mimicking an Odontogenic Cyst- A Case Report. Journal of Health and Allied Sciences NU. (2017):4: 2249-7110. 07. 10.1055/s-0040-1708736.Pellatt A. Stafne Bone Cavity: A Rare Case Affecting the Anterior Mandible. Clin Surg. (2019); 4: 2668Aps JKM, Koelmeyer  N, Yaqub  C. Stafne’s bone cyst revisited and renamed: the benign mandibular concavity. Dentomaxillofac Radiol (2020); 49: 20190475Stafne EC. Congenital defect of the mandible containing salivary gland tissue. In: Stafne E. C, ed. Oral Roentgenographic Diagnosis. 2nd Ed. . Philadelphia and London: WB Saunders Company; (1963); pp. 43–6.Hisatomi M, Munhoz L, Asaumi J, Arita E-S. Stafne bone defects radiographic features in panoramic radiographs: assessment of 91 cases. Med Oral Patol Oral Cir Bucal (2019); 24: e12–19. doi: https://doi.org/10.4317/medoral.22592Philipsen HP, Takata T, Reichart PA, Sato S, Suei Y. Lingual and buccal mandibular bone depressions: a review based on 583 cases from a world-wide literature survey, including 69 new cases from Japan. Dentomaxillofac Radiol (2002); 31: 281–90. doi: https://doi. org/10.1038/sj.dmfr.4600718Quesada-Gómez C, Valmaseda-Castellón E, Berini-Aytés L, Gay-Escoda C. Stafne bone cavity: a retrospective study of 11 cases. Med Oral Patol Oral Cir Bucal (2006); 11: e277–80Shigematsu H, Suzuki S, Osuga T, Okumura Y, Fujita K. A radiographical classification of Stafne’s bone cavity. Oral Radiol (1993); 9: 13–18. doi: https://doi.org/10.1007/BF02351544Shimizu M, Osa N, Okamura K, Yoshiura K. Ct analysis of the Stafne’s bone defects of the mandible. Dentomaxillofac Radiol (2006); 35: 95–102. doi: https://doi.org/10.1259/dmfr/71115878Araujo F, Marques TM, Correia A, Silva A. Differetial diagnosis of a salivary gland bone defect by means of a computerized tomography: A case report. Rev Odontotocienc (2009); 24:218:20Choudry AB, Chordia T, Chaudhary SM, Kumhare S, Varangaonkare C, et al. Stafne bone cyst- a case report. IOSR J Dent Med Sci (2016); 15:12—3.John S, Sripathi R, Gunachandara R, Arvind R. Stafne bone cyst- case report. Sch J Dent Sci (2015); 2:367-9Ariji E, Fujiwara N, Tabata O, Nakayama E, Kanda S, Shiratsuchi Y, et al. Stafne’s bone cavity. Classification based on outline and content determined by computed tomography. Oral Surg Oral Med Oral Pathol. (1993); 76:375-80.Adisen MZ, Yilmaz S, Misirlioglu M, Atil F. Evaluation of volumetric measurements on CBCT images using stafne bone cavities as an example. Med Oral Patol Oral Cir Bucal . (2015);20(5):e580-e586. Published 2015 ;Sep 1. doi:10.4317/medoral.20633Chaweeborisuit P, Yurasakpong L, Kruepunga N, Tubbs RS, Chaiyamoon A, Suwannakhan A: The prevalence of Stafne bone cavity: a meta-analysis of 355,890 individuals. J Dent Sci. (2023), 18:594-603. 10.1016/j.jds.2022.08.022Sisman Y, Etöz OA, Mavili E, Sahman H, Tarim Ertas E. Anterior Stafne bone defect mimicking a residual cyst: a case report. Dentomaxillofac Radiol (2010); 39: 124–6. doi: https://doi.org/10. 1259/dmfr/49320253 14.Katz J, Chaushu G, Rotstein I. Stafne’s bone cavity in the anterior mandible: a possible diagnostic challenge. J Endod (2001); 27: 304–7. doi: https://doi.org/10.1097/00004770-200104000-00020Kim H, Seok JY, Lee S, et al.: Bilateral Stafne bone cavity in the anterior mandible with heterotopic salivary gland tissue: a case report. Korean J Pathol. (2014); 48:248-9. 10.4132/KoreanJPathol.2014.48.3.248Arya 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);31:40-4Whaites E. Differential diagnosis of radiolucent lesions of the jaws. In: Whaites E, Drage N, eds. Essentials of dental radiography and radiology. Churchill Livingstone Edinburgh. 5th Ed; (2013); pp. 333–58.Murdoch-Kinch CA. Craniofacial Anomalies. In: White S. C, Pharoah M. J, eds. Oral radiology. Principles and interpretation. 7th Ed. . Canada: Elsevier; (2014); pp. 612–29.Koenig L. Mandible and Maxilla. Section 3. In: Koenig L, ed. Diagnostic imaging. Oral and maxillofacial. 1st ed: Amirsys; 2012.Mancuso AA, Pettigrew JC, Nair MK. Mandible: introduction and general principles. In: Mancuso A. A, Hanafee W. N, eds. Head and neck radiology. 1. Philadelphia: Wolters Kluwer Lippincott Williams & Wilkins; (2011);508–18.Larheim TA, Westesson P-LA. Jaw cysts and cyst-like conditions. In: Larheim T. A, Westesson P. -L. A, eds. Maxillofacial imaging. Springer. 2nd Ed.; (2018); pp. 23–56.MacDonald D. Radiolucencies. In: MacDonald D, ed. Oral and maxillofacial radiology. A diagnostic approach: Wiley-Blackwell West Sussex; (2011); pp. 93–150.Graham RM, Duncan KA, Needham G. The appearance of Stafne’s idiopathic bone cavity on magnetic resonance imaging. Dentomaxillofac Radiol (1997); 26: 74–5. doi: https://doi.org/10. 1038/sj.dmfr.4600224.Branstetter BF, Weissman JL, Kaplan SB. Imaging of a Stafne bone cavity: what Mr adds and why a new name is needed. AJNR Am J Neuroradiol (1999); 20: 587–9Segev Y, Puterman M, Bodner L. Stafne bone cavity–magnetic resonance imaging. Med Oral Patol Oral Cir Bucal (2006); 11: e345– 7.Bornstein MM, Wiest R, Balsiger R, Reichart PA. Anterior Stafne’s bone cavity mimicking a periapical lesion of endodontic origin: report of two cases. J Endod (2009); 35: 1598–602. doi: https://doi.org/10.1016/j.joen.2009.08.008Li B, Long X, Cheng Y, Wang S. Cone beam CT sialography of Stafne bone cavity. Dentomaxillofac Radiol (2011); 40: 519–23. doi: https://doi.org/10.1259/dmfr/84472023Friedrich RE, Zustin J, Scheuer HA, Assaf AT, Gröbe A. An unilateral basal bone defect of the mandible occupied by fatty tissue: Stafne’s cavity. In Vivo (2012); 26: 1045–8Mauprivez C, Sahli Amor M, Khonsari RH. Magnetic resonance sialography of bilateral Stafne bone cavities. Journal of Oral and Maxillofacial Surgery (2015); 73: 934.e1–934.e7. doi: https://doi. org/10.1016/j.joms.2015.01.034More CB, Das S, Gupta S, Patel P, Saha N. Stafne’s bone cavity: a diagnostic challenge. J Clin Diagn Res (2015); 9: ZD16–19. doi: https://doi.org/10.7860/JCDR/2015/14273.6772Soares A, Ferreira L, Calderipe C, et al. Stafne’s bone defect: a systematic review. Med Oral Patol Oral Cir Bucal . (2023);28(3):e264-e271. Published 2023 May 1. doi:10.4317/medoral.25676..Legends to figuresFig. 1 : CT OPG A well demarcated radioluscent lesion in the left body of the mandible adjacent to the lower borderFig. 2A : Axial CT scan highlighting thinning of the buccal cortexFig. 2B : Sagittal CT scan shows a sclerotic border outlining the radiolucent lucent lesionFig.3A & 3B : reformatted imaging illustrating the three dimension erosion of the lesion in the body of the mandible both buccally and linguallyFig.4: Hematoxylin and Eosin stain tissue (MagnificationX40)showing salivary glandular tissue ( presence of acini, ducts) and adipose tissue