Home About us Editorial board Ahead of print Current issue Archives Submit article Instructions Subscribe Search Contacts Login 
  • Users Online: 598
  • Home
  • Print this page
  • Email this page

 Table of Contents  
Year : 2016  |  Volume : 28  |  Issue : 4  |  Page : 458-461

Unicameral bone cyst: An unusual presentation

1 Department of Oral Medicine and Radiology, S.B. Patil Dental College and Hospital, Bidar, Karnataka, India
2 Department of Oral and Maxillofacial Surgery, S.B. Patil Dental College and Hospital, Bidar, Karnataka, India

Date of Submission12-Mar-2016
Date of Acceptance01-Feb-2017
Date of Web Publication21-Feb-2017

Correspondence Address:
Dr. Rajeshwari Javali
Department of Oral Medicine and Radiology, S.B. Patil Dental College and Hospital, Bidar, Karnataka
Login to access the Email id

Source of Support: None, Conflict of Interest: None

DOI: 10.4103/jiaomr.JIAOMR_27_16

Rights and Permissions

Unicameral bone cysts are encountered commonly in the proximal metaphyseal region of the long bones in children and adolescents. Identical lesions with similar etiology are found mostly in the mandible. Clinically, these lesions are usually asymptomatic, and the majority of cases are diagnosed fortuitously by chance as radiographic findings. Normally, they are empty cavities sometimes having a thin lining of connective tissue without epithelium containing serosanguinous fluid, clots, erythrocytes, fibrin and giant cells. Symptoms include swelling, pain, and rarely, labial paresthesia. Over half of the patients give a history of significant trauma to the area. Here, we present a case of unicameral cyst in an 8-year-old patient who presented with pain, swelling, and both buccal and lingual cortical plate expansion with no significant history of trauma.

Keywords: Bone cavity, traumatic bone cyst, unicameral bone cyst

How to cite this article:
Javali R, Sharma D, Bhagwati B. Unicameral bone cyst: An unusual presentation. J Indian Acad Oral Med Radiol 2016;28:458-61

How to cite this URL:
Javali R, Sharma D, Bhagwati B. Unicameral bone cyst: An unusual presentation. J Indian Acad Oral Med Radiol [serial online] 2016 [cited 2022 Oct 7];28:458-61. Available from: https://www.jiaomr.in/text.asp?2016/28/4/458/200641

   Introduction Top

Unicameral bone cyst is also called as simple bone cyst, traumatic bone cyst, traumatic hemorrhagic cyst, progressive bone cavity, solitary bone cavity, solitary bone cyst, idiopathic bone cavity, and hemorrhagic bone cyst, reflecting the uncertainty about the nature of this lesion. Unicameral bone cyst was first recognized by Virchow in 1876. In Dentistry, Lucas and Blum in 1929 for the first time reported three cases and described it as a separate disease entity.[1] The World Health Organization (WHO) in 1992 defined it as an intraosseous cyst having a tenuous lining of connective tissue with no epithelium.[2] The most commonly accepted theory is intramedullary hemorrhage after trauma. Traumatic bone cysts occurs most commonly during the childhood and adolescence, usually in the second decade of life. Some reports suggest that males are affected more often than females in a ratio of 3:2.[2] In the maxillofacial region, premolar-molar region of the mandible is most commonly involved than the maxilla. Clinically, it is asymptomatic, and is radiographically diagnosed as a well-defined unilocular radiolucency with scalloping in between the roots. Here, we present a case with unusual presentation of unicameral bone cyst, which presented with pain, swelling, and buccal and lingual cortical plate expansion in a child patient without any significant history of trauma.

   Case Report Top

An 8-year-old male patient reported to the Department of Oral Medicine and Radiology with a complaint of swelling in his lower right back region of the jaw since a year. The swelling was gradual in onset and attained the size of a large date, with mild discomfort on chewing. On further questioning, the patient did not reveal any history of trauma. Past medical and dental history was non-contributory. On extraoral examination, a diffuse swelling was obvious in the right mandibular region extending anterioposteriorly from the parasymphyseal region to the angle and superioinferiorly from a line joining the corner of the mouth to the lobule of the ear up to 1 cm below the inferior border of the mandible [Figure 1]. Intraorally, nontender, bony expansion on the buccal and lingual side was palpated in the region of 84, 85, and 46 [Figure 2]. A clinical diagnosis of dentigerous cyst was made taking into account the age of the patient and assuming an impacted tooth to be the etiology of the swelling.
Figure 1: Extraoral swelling on the right side of the mandible

Click here to view
Figure 2: Intraoral swelling

Click here to view

An orthopantomogram (OPG) revealed a well-defined radiolucency extending from the distal aspect of 83 to the mesial aspect of 46 of approximately 5 × 2 cm size, roughly oval in shape, and having scalloped borders between the tooth buds of 44, 45 and erupting 46. The lesion caused superior displacement of 44, 45 tooth buds with inferior bowing and irregular thinning of the cortex of the mandible [Figure 3]. Mandibular right lateral occlusal radiograph revealed a well-defined ballooning out of the buccal cortical plate, as well as mild expansion of the lingual cortical plate extending from the tooth bud of 83 to the distal aspect of 46. The internal structure revealed complete radiolucency [Figure 4]. Unicystic ameloblastoma and odontogenic keratocyst were considered as possible radiographic differential diagnoses. The patient underwent routine hematological investigations prior to incisional biopsy; all the values were in the normal range.
Figure 3: OPG revealing well defined radiolucency extending from distal aspect of 83 to mesial aspect of 46 having scalloped borders. Superiorly displaced tooth buds of 45 and 46 with expansion of inferior border of the mandible

Click here to view
Figure 4: Mandibular right lateral occlusal radiograph shows ballooning out of the buccal cortical plate with slight lingual plate expansion from 83 tooth bud to 46

Click here to view

Under local anesthesia, aspiration of the lesion yielded straw-colored fluid [Figure 5], and the lesion was found to be an apparently empty cavity without any epithelial lining showcasing inferior alveolar nerve bundle within it [Figure 6]. Curettage was performed and a small portion of the bone, which was excised to enter the bony cavity, was sent for histopathological examination. The bony cavity was closed with the buccal mucoperiosteal flap and sutured. The histopathological examination showed normal appearing bone spicules with parts of vascular connective tissue. Thus, on the basis of clinical, radiographical, and histopathological findings, a final diagnosis of unicameral bone cyst was made. The patient was followed up after a week for suture removal and intraoral examination revealed uneventful healing.
Figure 5: Straw-colored aspirate

Click here to view
Figure 6: Intraoperative view revealing empty cavity. Note the presence of inferior alveolar nerve bundle within the cavity

Click here to view

   Discussion Top

Unicameral bone cysts have been reported mostly in the long bones of the body such as the humerus and femur, with the involvement of jaw bones being uncommon.[3],[4] In jaw bones, an overwhelming majority of these cysts occur in the mandible and rarely in the maxilla. The etiology and pathogenesis is still debatable, however, the most widely accepted is the trauma-hemorrhage theory.

Olech et al. suggested the following possible pathogenesis based upon a traumatic etiology. Soon after trauma to a bone, there is intramedullary hemorrhage, a failure of early organization of the hematoma in some of the marrow spaces, and subsequent liquefaction of the clot can lead to the formation of a cyst. The primary hematoma will not be organized when not in contact with the reactive and fibrous connective tissue secondary to necrosis of the bone marrow itself and related endosteum. The trabeculae of medullary bone are then slowly resorbed by osteoclastic activity.[5] Other theories include the incapacity of the interstitial fluid to leave the bone secondary to inadequate venous drainage, benign neoplastic degenerative lesions, altered calcium metabolism local disturbances in bone growth, low-grade infections, venous obstruction, and bone tumors undergoing cystic degeneration,[6] frequently affecting the patients between 10 and 20 years of age.[3],[4]

Unicameral bone cysts are usually asymptomatic and are diagnosed incidentally during radiographic examinations. In the gnathic bones, three-fourth of the cases occur in the mandible than in the maxilla with the premolar-molar region being a favored site. We observed the cyst in the mandibular posterior region. However, cases involving the mandibular symphysis, ramus, condyle, and even anterior maxilla have been reported.[7] In Howe's survey, the majority of the cases (60%) were an incidental finding. Swelling was the presenting symptom in 27%, pain in 10%, while 2% complained of labial paresthesia, and in 2% there was both pain and swelling.[5] Our case is uncommon because the patient presented with both pain, swelling, and cortical plate expansion with no known history of trauma.

Radiographically, the cyst appears as a radiolucent area with scalloping in between the roots of the teeth, which is a diagnostic feature of unicameral bone cyst. Our case revealed similar radiographic finding of scalloping. Radiopaque foci and cloudiness can be observed in a few cases.[8] The borders may be irregular, well-defined, with or without cortication.[8],[9] Copete et al. classified the radiographic morphology of this cyst into four categories, namely, cone (64%), oval (16%), irregular (16%), and round (4%).[10] Other features include loss of lamina dura, teeth displacement, and root resorption.[9] The case presented here demonstrated superior displacement of tooth buds of premolars 44 and 45.

Although the majority of unicameral bone cysts are found at operation to contain only air, the fact that some contain blood or serosanguinous fluid tends to support the concept of a hematoma breaking down. Microscopically, a thin band of vascular fibrous connective tissue without epithelial lining is appreciated. The treatment of this cyst is surgical exploration and curettage to induce new hemorrhage. This new hemorrhage is in contact with the healthy connective tissue of the flap necessary to initiate organization of the clot, paving the way to induce new bone formation thus healing the cyst.

In most cases, cure or recurrence is confirmed within 3 years after the surgery. Mathew et al. stated that radiographic features such as absence of lamina dura, scalloped margins, nodular bone expansion, internal radiopaque masses, and/or multiple cavities were suggestive of increased likelihood of recurrence following treatment.[8] Although observed in few cases, recurrence of unicameral bone cysts is extremely uncommon with excellent prognosis. Our case was followed up after a period of 6 months after the surgery with clinically no significant swelling, pain, or expansion of cortical plates. The patient was further instructed to follow-up every year for another 2 years to check for the recurrence of the cyst.

   Conclusion Top

Unicameral bone cyst is an uncommon cyst diagnosed by incidental radiographic finding. This case is unique in a way that the patient presented with pain and swelling in the mandibular region with serosanguinous fluid aspirate. Moreover, radiographs did not exhibit the classical presentation.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

   References Top

Suei Y, Taguchi A, Tanimoto K. A comparative study of simple bone cysts of the jaw and extracranial bones. Dentomaxillofac Radiol 2007;36:125-9.  Back to cited text no. 1
Ajila V, Gopakumar R, Hegde S, Babu S, Harini K. Unusual presentation of solitary bone cyst- A case report. NUJHS 2014;4:135-7.  Back to cited text no. 2
Copete MA, Kawamata A, Langlais RP. Solitary bone cyst of the jaws. Radiographic review of 44 cases. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1998;85:221-5.  Back to cited text no. 3
Fregnani ER, Ramos FMM, Nadalin MR, Silva-Sousa YTC, Perez DEC. Simple bone cyst: Possible misdiagnosis in periapical pathology. Gen Dent 2007;55:129-31.  Back to cited text no. 4
Shear M, Speight PM. Cysts of the Oral and Maxillofacial Regions. 4th ed. Oxford, United Kingdom: Blackwell Munksgaard; 2007. p. 156-61.  Back to cited text no. 5
Matsumura S, Murakami S, Kakimoto N, Furukawa S, Kishino M, Takeshi I, et al. Histologic and radiographic findings of the simple bone cyst. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1998;85:619-25.  Back to cited text no. 6
Hansen L, Sapone J, Sproat R. Traumatic bone cysts of jaws. Report of sixty-six cases. Oral Surg 1974;37:899-910.  Back to cited text no. 7
Mathew R, Omami G, Gianoli D, Lurie A. Unusual cone-beam computerized tomography presentation of traumatic (simple) bone cyst: Case report and radiographic analysis. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2012;113:410-3.  Back to cited text no. 8
Baqain ZH, Jayakrishnan A, Farthing PM, Hardee P. Recurrence of a solitary bone cyst of the mandible: Case report. Br J Oral Maxillofac Surg 2005;43:333-5.  Back to cited text no. 9
Copete MA, Kawamata A, Langlais RP. Solitary bone cyst of the jaws: Radiographic review of 44 cases. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1998;85:221-5.  Back to cited text no. 10


  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6]


Similar in PUBMED
   Search Pubmed for
   Search in Google Scholar for
 Related articles
Access Statistics
Email Alert *
Add to My List *
* Registration required (free)

   Abstract Introduction Case Report Discussion Conclusion Article Figures
  In this article

 Article Access Statistics
    PDF Downloaded197    
    Comments [Add]    

Recommend this journal