Traumatic bone cyst mimicking radicular cyst

Abstract

Traumatic bone cysts were first defined by Lucas and Blum in 1929. It is classified as an intraosseous pseudocyst. They are asymptomatic and are usually seen during routine radiographical examination. According to the 2002 classification of the WHO, traumatic bone cysts are in miscellaneous lesions. This report describes a 16-year-old male patient who had a traumatic bone cyst that mimicked a radicular cyst.

Background

Possible diagnosis of traumatic bone cyst should be evaluated especially in young patients with radiolucent lesions whose related teeth are vital.

Case presentation

A 16-year-old male patient was referred to Istanbul University, Faculty of Dentistry, Oral and Maxillofacial Surgery Department by a dentist owing to a lesion in the mandible that had poor prognosis despite endodontic treatment performed on the teeth.

The lesion was asymptomatic and the patient reported a local trauma.

Physical examination showed no lymphadenopathy, no buccal or lingual expansion. Radiological examination revealed a bone cavity on the left mandible under the level of canine and first premolar apexes. The cavity's borders are ill defined (figure 1). Initial diagnosis was radicular cyst. Surgery was performed with local anaesthesia. Incision was made from right first incisor to right second premolar and full-thickness mucoperiostal flap was elevated. Corticotomy of the cysts was carried out and bone cavity was seen. No cystic capsule was found (figure 2). Curettage was made for haemorrhage and the flap was closed with 3–0 silk suture. Postoperative 5-month radiographical evaluation showed bone cavity filled with new bone tissue (figure 3).

Figure 1.

Preoperative panoramic radiography of the patient.

Figure 2.

Intraoperative image of the patient.

Figure 3.

Postoperative 5-month panoramic radiography of the patient.

Differential diagnosis

Traumatic bone cysts radiographies could be mistaken with keratocystic odontogenic tumour because of little expansive growth and scalloped borders. It might also be mistaken for radicular cysts.

Discussion

Traumatic bone cysts were first defined by Lucas and Blum.¹ It is classified as an intraosseous pseudocyst. Traumatic bone cysts are known by different names in the dental literature by time: haemorrhagic, solitary, extravasion and simple bone cyst.^1–5 They are asymptomatic and are usually seen during routine radiographical examination.

According to the 2002 classification of the WHO traumatic bone cysts are in miscellaneous lesions.⁶ The present report describes a traumatic bone cyst that mimics a radicular cyst.

Traumatic bone cysts are mostly seen in long bones especially metaphysis of the proximal humerus and femur. They are rarely seen in the maxillofacial region.^{7 8} Lesions are seen frequently in the second decade. In the maxillofacial region they are usually seen between the mandibular canine and third molar and mandibular symphysis.⁹ For the present case, the cyst was seen between the mandibular left canine and first premolar which is consistent with the literature.

Aetiology of the traumatic bone cyst is uncertain. According to a widely accepted theory, haematoma is caused by trauma that is not organised and repaired. Meanwhile, adjacent bone tissue is destroyed by osteoclastic activity and bone cavity occurs.^{10 11} Although the present theory is widely accepted in the dental literature, it is not sufficient to explain lesions at metaphysis and diaphysis of proximal humerus in orthopaedics. The same theory is also insufficient to clarify traumatic bone cysts enlarged in time.¹² Cystic degeneration of the primary bone tumours, venous obstructions, increased osteolysis, low-grade infection, local defects in bone growth, ischaemic necrosis of bone marrow and calcium metabolism diseases are the other theories.^{8 13}

Traumatic bone cysts are usually asymptomatic, but pain complaint is present for 10–30% of the cases.⁸ Pathological fractures are seen in patients with traumatic bone cysts.⁷ Traumatic bone cavity is generally diagnosed during routine radiographical examinations accidentally.⁹

It is not expected that traumatic bone cysts will change the vitality and mobility of teeth. They also do not displace teeth.⁹ It is seen in radiographies as multilocular or unilocular radiolucent lesions. Borders of the cavity are variable from well-defined to ill-defined. The characteristic feature of the lesion is radiolucent image scallop between the roots when several teeth are included.¹⁴ Traumatic bone cysts radiographies could be mistaken for keratocystic odontogenic tumour because of little expansive growth and scalloped borders.¹⁴ For the present case, radiographical examination showed no dislocation of teeth and well-defined radiolucent bone cavity. In our case, the clinician who referred the patient to the Oral and Maxillofacial Surgery Department misdiagnosed the lesion as a radicular cyst because of the lesion's relationship with teeth apexes and lack of knowledge about the lesion's effect on teeth vitality. In addition, owing to ignoring local trauma we misdiagnosed the lesion as a radicular cyst.

Sex distribution is approximately equal but men can be affected more frequently.^{9 12} For our case, the patient was male and this is in accordance with the literature.

Learning points.

• Possible diagnosis of traumatic bone cyst should be evaluated especially in young patients with radiolucent lesions whose related teeth are vital.

• Trauma history must be questioned. CT scan which is an advanced imaging technique has an important diagnostic value for initial diagnosis.