Aneurysmal bone cyst of the mandible: A case report

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Pediatric Dental Journal journal homepage: www.elsevier.com/locate/pdj

Case Report

Aneurysmal bone cyst of the mandible: A case report Shina Mohd Ariffin*, Noraini Nun Nahar Yunus Department of Paediatric Dentistry, Paediatric Institute, Kuala Lumpur Hospital, Jalan Pahang 50586, Kuala Lumpur, Malaysia

article info

abstract

Article history:

Aneurysmal bone cyst (ABC) is a relatively rare, benign osteolytic lesion that typically in-

Received 31 March 2014

volves long bones. Approximately 2% of this tumour occurs in the jaws, with the posterior

Received in revised form

portion of the mandible being the predominant site. This lesion usually presents in the first

31 July 2014

two decades of life without sex predilection. Clinically and radiographically, ABCs are

Accepted 11 September 2014

known for their diverse features, therefore often posing a diagnostic dilemma.

Available online 28 October 2014

This is the case report of a 2 year old boy with hereditary Thrombocytopenia, who was referred to us for management of his symptomatic, non healing traumatic ulcer on the

Keywords:

right buccal mucosa and swelling of his right cheek. The lesion was initially diagnosed as

Aneurysmal bone cyst

haemangioendothelioma by the referring Hospital. Based on the MRI, panaromic radio-

Benign osteolytic lesion

graph and CT images, the lesion is suggestive of ameloblastoma of the right mandibular.

Thrombocytopenia

Histopathological examination revealed that the lesion is consistent with ABC. The lesion

Diagnosis

was treated by surgical curettage under general anaesthesia. After one year follow up,

Treatment

clinical signs and symptoms have resolved well. As ABCs are known for its various clinical and radiological features and severity, histopathological examination is essential for definitive diagnosis and management. Copyright © 2014 The Japanese Society of Pediatric Dentistry. Published by Elsevier Ltd. All rights reserved.

1.

Introduction

The aneurysmal bone cyst (ABC) is a relatively rare, benign osteolytic lesion and considered to be a pseudocyst due to the lack of epithelial lining [1,2]. This type of lesion was first reported by Jaffe and Liechtenstein in 1942 [3]. In 1958, Bernier and Bhashkar first reported a case which occurred in the jaws [4]. The World Health Organisation (WHO) defines ABCs as “a

benign tumour-like, expansive osteolytic lesions consisting of blood-filled spaces and channels divided by connective tissue septa that can contain osteoid tissue and osteoclastic giant cells [1,5,6]. This lesion is predominantly located within the long bones metaphysis like the femur (more than 50%) and the tibia (12%e30%) and also 20% in the vertebral column [1,2,7e10]. The occurrence is extremely rare in the craniofacial region and only 1e3% involves the jaws [1,2,5,7,8,10]. Of these, the

* Corresponding author. Tel.: þ60 3 2615 5805 (work), þ60 1 0231 0109 (mobile); fax : þ60 3 2615 6420. E-mail addresses: [email protected], [email protected] (S. Mohd Ariffin). http://dx.doi.org/10.1016/j.pdj.2014.09.001 0917-2394/Copyright © 2014 The Japanese Society of Pediatric Dentistry. Published by Elsevier Ltd. All rights reserved.

p e d i a t r i c d e n t a l j o u r n a l 2 4 ( 2 0 1 4 ) 1 7 8 e1 8 3

mandible is more affected when compared to the maxilla (3:1) [2,9,11]. The mandibular body and ramus are the predominant sites with infrequent cases at the coronoid process and condyle [2,9]. ABC usually presents in adolescents, mostly those younger than 20 years of age with no gender predilection [8,10]. The clinical signs and symptoms of ABC are diverse and non specific while their radiographic features are not pathognomonic [1,5,9]. Hence, it may lead to further diagnostic difficulties and diagnostic dilemma [1,5,9]. In addition, although ABC are non-neoplastic benign lesion, occasionally they may behave as a locally aggressive, rapidly expanding and locally destructive mass which may be misdiagnosed as a malignant neoplasm [9,12]. This report presents a case of ABC at the posterior right mandible which was managed by conservative curettage in a 2 year old boy.

2.

Case report

A 2 year old Malay boy was referred to the Department of Paediatric Dentistry, Kuala Lumpur Hospital (KLH) for management of his symptomatic, non healing traumatic ulcer on the right buccal mucosa with persistent swelling of his right cheek. The patient's mother reported that the patient had a fall early September 2012 while playing and bit his right cheek and his cheek has been progressively growing larger since. A few days later, the mother noted an ulcer has developed at his inner right cheek with mild swelling. The patient sought dental consultation and was prescribed oral antibiotic for his right buccal mucosa ulceration secondary to traumatic cheek biting. The following day, the patient attended another dental consultation at a private hospital and was prescribed a course of Amoxicillin clavulanate and Cefuroxime antibiotics. Within the next week, both extra oral and intra oral lesions subsided slightly but the ulcer still persisted with no episode of intra oral bleeding. In mid September 2012, the patient was admitted for enlarged right cheek swelling and reduced oral intake. He was placed on intravenous Rocephin and was discharged a week later. He was readmitted early October 2012 for persistent right cheek swelling with spiking temperatures. He was started on intravenous Meropenem and Metronidazole. First episode of intra oral bleeding from the lesion was reported on day 2 of readmission. An incisional biopsy and decompression of the cheek swelling was scheduled under general anaesthetic on day 3 of readmission. However, the procedure was deferred when bleeding was observed from the gingival crevice of the lower right second deciduous molar intra operatively. A Computer Tomography (CT) scan of the region was done and the lesion was initially diagnosed as haemangioendothelioma. The patient was then referred to the Department of Paediatric Dentistry KLH for further management. The patient first presented to our clinic mid October 2012. Generally, the patient was active, alert and responsive with no significant weight loss. Medically, he was recently diagnosed with hereditary thrombocytopenia, his first blood transfusion was prior to the scheduled incisional biopsy. Family history revealed both the father and paternal grandfather as known

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cases of hereditary Thrombocytopenia without any history of blood transfusion. The patient also had mild eczema. No other previous history of hospitalisation and medical issues or allergies noted. Extra oral examination revealed a right facial asymmetry with a diffuse swelling on the right cheek measuring approximately 30 mm in diameter. Digital palpation showed firm texture with slight tenderness but without bruits, warmth or egg-crackling sign. The overlying skin appeared normal (Fig. 1). However, multiple haematomas were observed on his arm and legs (Fig. 2). Intra oral assessment revealed lobulated swelling arising from the right buccal mucosa extending into the occlusal plane measuring approximately 20 mm by 20 mm. The overlying mucosa appears to be normal except for some petechial spots and inflammation at the area of indentation most likely when deciduous right second molars occluded. The deciduous upper right and lower right molars were firm. The deciduous lower right second molar was displaced lingually. Otherwise, oral hygiene was good with a caries free dentition (Fig. 3). An urgent blood assay was ordered to rule out the possibilities of Haemophilia and Von Willebrands disease. Blood assay results were all within normal range (Table 1). A panaromic radiograph showed expansion of the right mandible at the body and ramus replaced by multilocular radiolucencies with multiple small sclerotic foci. There was thinning of the cortical outline but no evidence of cortical destruction. There was a single round radiolucency depicted in the body of the left mandible lateral to the permanent first molar which may represent tooth follicle of the permanent second molar. On the affected side, the permanent right first molar tooth and permanent second molar follicle were displaced by the lesion (Fig. 4). Computer Tomography (CT) scans taken previously confirmed the presence of a large lesion involving the right mandibular body and ramus causing expansion of the bone. There were multiple bony septa with soft tissue density within the bone. On post contrast images there was linear enhancement detected but no definite soft tissue enhancing mass was noted. Both temporomandibular joints and pterygoid plates were normal (Fig. 5). On the Magnetic Resonance Imaging (MRI) the lesion was heterogenous predominantly isointense to the adjacent soft tissue on T1 and appeared as multiloculated low signal lesion

Fig. 1 e Clinical photograph showing the right facial asymmetry with diffused swelling of the right cheek.

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Fig. 2 e Clinical photographs showing multiple haematomas present. A: Left elbow, B: Legs.

on T2. Post contrast study showed enhancement of the capsule and the septae. Again, no definite soft tissue enhancing mass was demonstrated. There was no definite cystic component or fluidefluid level. The mass was causing compression to the adjacent right submandibular gland, masseter and pterygoid muscle but with clear fat plane demonstrated in between (Fig. 6). With the hereditary thrombocytopenia monitored by the medical colleagues, an excisional biopsy and surgical curettage of the lesion was performed under general anaesthesia and the tissue was sent for histopathologic evaluation (Fig. 7). The microscopic examination report revealed occasional spaces, which were not lined by endothelium, filled with red blood cells surrounded by cellular fibroblastic tissue, woven bone and occasional multinucleated giant cells. Fig. 8 shows histological images of the biopsy specimen. From the histopathologic examination, the lesion was consistent of aneurysmal bone cyst. Post operative one week review was uneventful with right check swelling subsiding and healing demonstrated at the right buccal mucosa biopsy site. Subsequent regular reviews up to one year were uneventful with no sign of recurrence observed (Fig. 9). The patient was still under regular follow up.

Fig. 3 e Clinical presentation of the intra oral lesion. Lobulated swelling of the right buccal mucosa and displacement of the deciduous lower right second molar.

3.

Discussion

Aneurysmal bone cysts have been fairly established since its description by Jaffe and Lichtenstein in 1942 and later clinically reported in 1958 by Bernier and Bhaskar. However, throughout the years until present day, literatures have reported that authors are in agreement that the ultimate origin, aetiology and pathogenesis of ABCs are unclear, highly debatable and remain controversial [5,6,8,10,13]. One theory states that ABC can develop as either a primary or secondary lesion that is associated with other bone diseases [2,8].

Table 1 e Blood Assay results. Factor VIII assay and VWF Ag are within normal range. Test APTT PT Factor VIII assay VWF Ag Fbg

Results

Normal value

32.3 s 11 s 145.3% 104.4% 238

24e38 s 11e17 s 50e200% 50e200% 200e400 (mg/dL)

Fig. 4 e Panaromic X-ray (dated 11.10.2012) showing expansion of the body and ramus of the right mandible replaced by multilocular radiolucencies with multiple small sclerotic foci. There is thinning of the cortical outline but no evidence of cortical destruction. The permanent right first molar tooth and second molar follicle is displaced by the lesion.

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Fig. 5 e Axial CT image of the lesion showing the expansion of the bone at the right posterior mandible with multiple bony septa present.

Another theory reported that a traumatic history and subperiosteal haematoma formation essentially predisposes to the development of ABC [2,8,13]. However, Tillman et al. have reported nearly 100 cases with no history of associated trauma [14]. Other literature reviews concluded that ABC occurs secondary to a pre-existing lesion and that central giant cell granuloma appears to be the most common lesions [8,13]. One widely accepted theory by Jaffe and Lichenstein which proposed that local haemodynamic alteration causes increased venous pressures and engorgement of the vascular bed in the transformed bone hence leading to resorption, connective tissue replacement and osteoid formation [3,8,13]. Other researchers suggested that ABC can also be classified as primary and secondary. Primary ABC could be of congenital or acquired and could originate from pre-existing Arterio-Venous

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malformations [8]. While secondary type is reported to be associated with degeneration of pre-existing lesions such as a cyst, tumour or fibro-osseous lesion [2,8,13]. Literatures have also reported familial incidence of ABC [8,10]. For this patient, the mother reported that the child had history of falls which caused the cheek swelling and cheek ulcer. Therefore, in the present case, the pathogenesis of ABC could be associated to the predisposing traumatic incidents. Clinically, ABCs are known for their diverse presentation ranging from small, indolent, asymptomatic, slowly expanding lesion to a rapidly expanding, destructive lesion mimicking malignancy which could cause extensive bone destruction, deformity, pain, swelling, neurological symptoms and pathologic fractures [5,9,10]. Although these lesions are reported to have no specific clinical presentations [13], however some typical clinical presentations have been documented in the literatures. Clinical presentations could include well-defined swelling which causes facial asymmetry, lesions that progressively enlarges with a history of rapid growth, firm swelling which may be non tender or slightly tender upon digital palpation, overlying skin and mucosa are normal and intra orally, malocclusion can be caused by displaced teeth which remains vital [9,15]. These typical presentations are consistent with our patient. Less common clinical presentations would be disesthesias, proptosis, diplopia, root resorption of teeth and progressive nasal obstruction [9,15]. Histologically, ABCs can be categorised into three types. Firstly, the “classic or vascular” form of ABC consists of multiple sinusosidal blood-filled spaces separated by fibrous septa, with multinucleated giant cells and osteoids. Generally hemosiderin is present in variable amounts and there is evidence of osteoid and bone formation [8e10]. The histological features of our case are consistent with this “classic” form of ABC. Secondly, the “solid” histological form of ABC is noncystic variant with solid grayewhite tissue with hemorrhagic foci and abundant of fibroblastic and fibrohistocytic elements with osteoid and calcifying fibro-myxoid tissue. The ‘mixed’ form consist of elements of both vascular and solid types [8e10]. The radiographic and CT features of ABCs are not pathognomonic and are rather conflicting [1,8]. Radiographically,

Fig. 6 e MRI showing the enlarged lesion divided by septa. Left: frontal view. Right: axial view.

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Fig. 7 e Intra-operative images. A: Prior to curettage. B: Post curettage. C: After closure.

the lesions may appear radiolucent, radio-opaque or mixed [10]. Panoramic radiographs usually depict a thinning at the cortical bone and multilocular, cystic radiolucent imaging with cystic meshwork divided by bony septa [9]. The bone may appear expanded, resembling a cystic honey comb or soap bubble and is eccentrically ballooned [8,10]. There may be destruction or perforation of the cortex, displaying a periosteal reaction which creates a “ray-sun” effect [9]. Our lesion is consistent with the bony expansion at the right posterior mandible with the radiolucent cystic honey comb appearance. CT scan may show multilocular or unicystic lesions and can accurately identifies the tissue septa [9,15]. Based solely on radiographic appearance, ABCs have similar appearance to Ameloblastoma, Myxoma, Central giant cell granuloma and also haemangioma [10]. For our case, by correlating the panaromic radiographs, CT and MRI, the radiologists reported that the most likely diagnosis was ameloblastoma. Dentigerous cyst and giant cell tumours were unlikely as there was no fluidefluid level observed. In addition, it was atypical

location for aneurysmal bone cyst. Hence, a biopsy was highly recommended for definite tissue diagnosis. Treatment of ABC is aimed at complete removal of the lesion [1,8] and the type of treatment modalities depends upon the size, site, nature and extent of the lesion [8,10]. Contemporary main treatment options are surgical curettage or partial resection [1]. ABCs are known to have a high recurrence rate of approximately 20e30% due to remnants of lesions and usually reoccur within the first 12 months after initial treatment [1,7,8,10]. Compared to partial resection, simple curettage has been reported to be associated with a higher recurrence rate ranges from 21 to 50% [6,8]. Conversely, few authors have also reported on the spontaneous regression of lesions and no reoccurrence noted following conservative curettage of mandibular lesions [8,10,16]. The present case was treated by curettage and regular monitoring. There was no evidence of any reoccurrence of lesion after a year of follow up. Based on this case report, the diagnosis of aneurysmal bone cyst can be challenging due to the variable

Fig. 8 e Histological image of biopsy specimens. Left: View of 2X. Right: View of 10X.

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Fig. 9 e Post operative images. A: Healing of right buccal mucosa 1 month post operatively. B: Right cheek swelling subsided 1 month post operatively. C: Panaromic X-ray taken 1 year post biopsy. Reduction in the bony expansion of the right mandibular body and ramus with thickening of the cortical outline.

clinicopathological, histological and radiographic presentations and often leads to a diagnostic dilemma and even misdiagnosis. Hence, proper investigations inclusive of MRI and histopathological analysis are essential for a final diagnosis.

Conflict of interest No conflict of interest.

references

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