|Year : 2015 | Volume
| Issue : 4 | Page : 608-611
An asymptomatic radiolucent lesion in posterior mandible: A case report
Keerthi Gurushanth1, Chaya M David2, Preeti Dhir3
1 Department of Oral Medicine and Radiology, KLE Society's Institute of Dental Sciences, Bengaluru, Karnataka, India
2 Department of Oral Medicine and Radiology, Dayananda Sagar College of Dental Sciences, Bengaluru, Karnataka, India
3 Department of Oral Medicine and Radiology, Desh Bhagat Dental College and Hospital, Muktsar, Punjab, India
|Date of Submission||07-May-2015|
|Date of Acceptance||18-May-2016|
|Date of Web Publication||19-Aug-2016|
Dr. Keerthi Gurushanth
#34, 4th A Main, Kalyananagar, Nagarbhavi Main Road, Bengaluru - 560 072, Karnataka
Source of Support: None, Conflict of Interest: None
| Abstract|| |
Radiolucent mandibular lesions are commonly evident on head and neck imaging and present a diagnostic dilemma for the radiologist. These may represent a broad spectrum of lesions arising from both odontogenic and nonodontogenic structures. Furthermore, few radiolucent lesions are often identified as incidental lesions by the radiologist on imaging performed for different reasons. Location of the lesion, borders, internal structure, and its effect on surrounding structures are the key points to narrow the differential diagnosis. Imaging is essential not only for the diagnosis of lesions, but also to guide therapy and monitor the treatment response. Here is a case report on traumatic bone cyst that presented as an asymptomatic radiolucent lesion in right posterior mandible and was discovered incidentally on routine radiograph. The lesion was diagnosed based on patient's anamnesis and radiographic examination. This paper aims at discussing the differential diagnosis, various radiological characteristics, and their prediction in prognosis of the lesion.
Keywords: Asymptomatic, incidental, mandible, radiolucent lesions, traumatic
|How to cite this article:|
Gurushanth K, David CM, Dhir P. An asymptomatic radiolucent lesion in posterior mandible: A case report. J Indian Acad Oral Med Radiol 2015;27:608-11
|How to cite this URL:|
Gurushanth K, David CM, Dhir P. An asymptomatic radiolucent lesion in posterior mandible: A case report. J Indian Acad Oral Med Radiol [serial online] 2015 [cited 2020 Aug 14];27:608-11. Available from: http://www.jiaomr.in/text.asp?2015/27/4/608/188774
| Introduction|| |
Traumatic bone cyst (TBC) is a benign, slow-growing lesion commonly affecting the mandible. These cysts are asymptomatic intraosseous pseudocysts discovered incidentally on routine radiographs.  The term TBC was first described by Lucas and Blum in 1929 as a separate disease entity. , It frequently occurs in the posterior mandible, with a higher incidence found among young individuals.  We report a case of TBC that was asymptomatic when presented; however, the radiograph revealed thick lingual cortical expansion, which is rarely reported. The purpose of this paper is to describe the various radiographic characteristics of TBC, its differential diagnosis and radiographic prediction in the possible prognosis of the disease.
| Case Report|| |
A 21-year-old male patient reported for a routine dental check-up. In patient's anamnesis, it was determined that he had trauma to his right jaw 7 months back. The medical history was non-contributory. On intraoral examination, all the teeth appeared normal except for mild deposits. There was food lodgment and periodontal pocket in relation to distal aspect of right third molar. Although the right first molar clinically appeared normal, it was tender on percussion [Figure 1]. Provisional diagnosis of apical periodontitis and localized periodontitis was considered in relation to right first molar and third molar, respectively. The associated and adjacent teeth were vital.
|Figure 1: Clinical photograph showing intact crowns of the right mandibular molars and food lodgment on the distal aspect of third molar and marginal gingiva of second molar|
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Intraoral periapical radiograph (IOPAR) showed angular bone loss in the interdental region of the first and second molars [Figure 2]. There was a well-defined radiolucency involving the periapical region of second premolar and molar, extending up to the mesial root of second molar with superior scalloped margins. The lamina dura of the associated teeth was intact. The panoramic radiograph (OPG) showed a well-defined radiolucency involving the periapical region of right first premolar to second molar and measured about 2.5 × 1 cm in diameter with superior scalloped margins and smooth corticated border inferiorly. The mandibular lateral occlusal radiograph demonstrated lingual cortical expansion [Figure 3]. Fine needle aspiration could not be performed due to thick cortical bone.
|Figure 2: IOPAR of the right mandibular molars showing angular bone loss between first and second molars and periapical radiolucency in the region of premolar and first molar with scalloped margins. Note the lamina dura of these teeth are intact|
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|Figure 3: Lateral mandibular occlusal view demonstrates lingual cortical expansion in the region of right first and second molars|
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Computed tomography (CT) images showed mild expansion of the body of mandible on the right side [Figure 4]. Well-defined oval osteolytic lesion measuring about 2.2 × 1 cm within the right half of the body of mandible in relation to the roots of right first premolar was noted. No evidence of root resorption or root fracture was noted. Left half of the mandible, mandibular canals, and ascending rami appeared normal [Figure 4] and [Figure 5]. An axial bone algorithm CT image showed lingual cortical expansion on the right half [Figure 4]a. Contrast-enhanced CT image was obtained to assess the vascularity within the lesion. Axial contrast-enhanced CT image with soft tissue algorithm showed homogenous hypodense area in the right mandible without any evidence of vascularity [Figure 4]b. Sagittal CT and coronal CT images obtained using soft tissue algorithm demonstrated hypodense region in the right mandible [Figure 4]c and d, respectively]. Radiographic diagnoses of TBC and odontogenic keratocyst were considered. All the parameters were found to be within normal range on routine hematological investigation. The cyst was surgically explored, curetted, and sutured [Figure 6]. Histopathological analysis revealed a bone wall cavity with no lining epithelium and with normal-appearing bone spicules having a few areas of vascular connective tissue that confirmed the diagnosis of TBC [Figure 7]. Postoperative recovery was uneventful.
|Figure 4: CT images revealing cystic lesion in the body of the right mandible. (a) An axial bone algorithm CT image showing lingual cortical expansion. (b) Axial contrast-enhanced CT image with soft tissue algorithm showing hypodense area in the right mandible. (c and d) Sagittal and coronal CT images obtained using soft tissue algorithm demonstrating hypodense region in the right mandible|
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|Figure 5: CT panoramic reconstruction revealing the extent of hypodense region in the body of the right mandible. Note the scalloped margins between the roots of first premolar and molars|
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|Figure 6: Clinical photograph showing (a) surgical exploration of the cyst and (b) sutures placed for primary wound closure|
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|Figure 7: Normal-appearing bone spicules with few areas of vascular connective tissue without epithelial lining (hematoxylin-eosin, original magnification ×40)|
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| Discussion|| |
TBCs account for only 1% of maxillofacial cysts and tumors.  They have been referred by different names like hemorrhagic bone cyst, simple bone cyst, hemorrhagic TBC, solitary bone cyst, progressive bone cavity, unicameral bone cyst, extravasation cyst, and idiopathic bone cavity. ,, The multitude of names for this lesion shows the lack of understanding of its etiopathogenesis. , The various theories proposed include trauma, local alteration of bone metabolism, low-grade infection, intraosseous vascular abnormalities and degeneration of bone tumors. , Among these, traumatic-hemorrhagic theory is the most accepted. ,, It suggests that lesions develop if intramedullary clots formed due to trauma do not undergo lysis or resolution. This theory thus explains why TBCs occur more often in young individuals. , Another theory suggests that there may be localized aberration in normal bone remodeling of metabolism, thus supporting indirectly that these cavities often occur inside the lesions of cement osseous dysplasia and fibrous dysplasia.
Clinically, most cases are asymptomatic and are discovered incidentally on routine radiographs. However, some studies reported symptoms in 30% of the cases. , The commonest symptom was pain; other symptoms were swelling, tooth sensitivity, tenderness, hypoesthesia, and pathological fracture.  Seventy-five percent of TBCs occur in femur and humerus, usually in the metaphysis close to the epiphyseal plate. Multiple TBCs occur with cemento-osseous dysplasia, especially seen in older population. ,
Radiographically, TBC appears as a well-defined radiolucent lesion, either unilocular or multilocular, with variable size. One unique feature of TBC is that it may occur in or across the midline. The classic feature of this lesion is that it lies above the inferior alveolar canal (IAC) and squeezes up between the roots of teeth producing scalloped/wavy appearance on superior margins; 70% of the cases have this feature. The margins may be well defined, corticated, thin, condensed, and intact. They may consist of irregular, discontinuous, almost interwoven areas of sclerotic bone and may appear as punched-out or a combination of these patterns. "Fallen trabecula sign" is found in TBC following fracture and in pathologic fracture, which has not been reported in literature so far. , Lamina dura of the adjacent roots appears to be intact, although resorption and displacement are noted in many cases. Thinning and expansion of the cortex may occur; inferior displacement or resorption of the cortex in IAC is also noticed.
Radiographic classification of TBC was suggested based on the findings of lamina dura. A study by Suei et al. has suggested that radiographs are not only used for diagnosis but also in predicting the prognosis of TBC.  The results showed that TBC lesions with intact lamina dura on the associated teeth healed after treatment; however, decision should be avoided in borderline cases. Absence of lamina dura, scalloped margins, cases with bone expansion, and the nature of expansion (smooth or nodular) are the possible signs of recurrence and help in predicting the prognosis of TBC. 
Keratogenic odontogenic tumor (KOT) has a similar radiographic appearance and is considered in differential diagnosis as it grows along the bone with little expansion and scalloped margins. However, KOTs usually have a more definite cortical boundary, resorb and displace teeth, and occur in an older age group. Malignant lesions can be excluded from consideration in the list of differential diagnosis due to lack of an invasive periphery and bone destruction in TBC. A healing cyst with new immature bone formation may falsely indicate the presence of ossifying fibroma or fibrous dysplasia.
Surgical exploration of the lesion and curettage of the lining lead to subsequent healing. A definitive diagnosis is achieved during surgery due to an empty bone cavity without epithelial lining. Sometimes the cavity contains straw-colored fluid or bright blood. , Spontaneous healing of the lesion has been reported. These lesions can recur rarely. Lesion progression may lead to pathological mandibular fracture. 
| Conclusion|| |
TBC is a pseudocyst most commonly affecting young individuals. The etiopathogenesis of TBC remains unclear. Trauma can be considered as an important factor in instigating the lesion. Most TBCs are discovered incidentally on radiographs. Thus, radiographs not only play a crucial role in diagnosis but also help in predicting the prognosis. Definitive diagnosis can be achieved at surgery when an empty bone cavity without epithelial lining is observed.
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