Giant recurrent aneurysmal bone cyst of the mandible.

The Aneurysmal bone cyst (ABC) is an infrequent but well defined lesion occurring most commonly in the long bones, the pelvis and vertebrae. Only 1-2% of the lesions are known to occur in the maxillofacial region. Clinically, the lesion usually occurs in young adults below 20 years of age. Though there does not seem to be any marked gender predilection and slight preponderance towards females has been reported. Here we present a case of giant recurrent aneurysmal bone cyst in a 19 year old male patient treated by segmental resection and reconstruction with vascularized fibular graft.

INTRODUCTION

Aneurysmal bone cyst (ABC) is described as a pseudo cyst due to the absence of epithelial lining. Jaffe and Lichtenstein in 1942 were the first to recognize and describe it as a distinct clinical and pathological entity. Bernier and Bhasker (1958) were the first to describe this entity in the jaw bones. The ABC is an infrequent but well defined lesion occurring most commonly in the long bones, the pelvis and vertebrae. Only 1-2% of the lesions are known to occur in the maxillofacial region. The lower jaw is more frequently affected in about 66% of cases; only 22 cases are reported in the maxilla.[12] In the mandible, the body and the mandibular ramus are more commonly involved. Rare cases of involvement of coronoid process and the mandibular condyle have been reported. Clinically, the lesion usually occurs in young adults below 20 years of age. And there does not seem to be any marked sex predilection. Slight preponderance towards females has been reported. Jaffe describes the word ‘aneurysmal’ as the blowout distension of part of the affected bone area. The bony expansion causes visible swelling over the underlying soft tissues. Usually an intact periosteum and a very thin shell of bone cover the cyst. The aim of this paper is to present a case of a large ABC in the mandible of a young patient and to discuss the controversies regarding the term GIANT ANEURYSMAL BONE CYST, its diagnosis and treatment with brief review of literature.

CASE REPORT

A 19 year old male patient presented with a swelling involving left side of the lower face for more than 6 months [Figure 1]. The swelling had rapidly grown in last 2 months and was also associated with pain at the left mandibular angle region. Patient had visited a dental surgeon for the above complaint 4 months back following which he underwent an intraoral procedure with extraction of his left lower third molar tooth under general anesthesia. One month after the procedure the swelling did not resolve and began to increase in size and was associated with pain. On examination there were no extraoral or intraoral draining sinuses or suppuration and patient was in good health with no medical problems except for the pain and swelling which extended from left angle region to the premolar-canine region [Figure 2]. The lesion was firm on palpation, slightly tender. The skin over the swelling was normal.

Figure 1

Diffuse swelling on the mandible

Figure 2

Preoperative OPG, shows multilocular radiolucency, with extension into the roots of teeth without any root resorption

Intraorally, the buccal vestibule was obliterated due to the expansion of the buccal cortical plate extending from the retro-molar region to the premolar-canine region. Overlying mucosa was pink and smooth. The teeth were not mobile.

Panoramic radiograph showed a lytic and expansive lesion showing a ‘honeycomb’ and soap bubble like appearance with defined margins [Figure 3]. Lytic lesion measured 7 cm × 5 cm in its greatest dimension with destruction of buccal and lingual cortical plates but maintaining continuity of the lower border.

Figure 3

Segmental resection of mandible with removal of whole lesion.

An incisional biopsy under local anesthesia was carried out and was suggestive of aneurysmal bone cyst.

Surgical treatment for resection of the mandible followed by immediate reconstruction with a vascularised fibula flap was planned as we concluded it to be a recurrence. Under general anesthesia, through an extraoral submandibular approach the tumor was exposed. The mandible was resected 1 cm beyond the radiographic margins both at the ramus and the premolar-canine regions [Figure 4]. The jaw cortex was ballooned out and thinned having an egg shell appearance, but without loss of continuity. There was infiltration into the soft tissues at areas of perforation of the buccal cortex, which was cleared. Primary reconstruction of the defect was carried out with a vascularised fibula flap [Figures 5 and 6] harvested from the right leg and secured with a titanium reconstruction plate [Figure 7]. There was no significant blood loss during surgery. Patient was put on intermaxillary fixation for three weeks.

Figure 4

Vascularized fibula

Figure 5

Vascularized fibula reconstruction of mandible

Figure 6

Photomicrograph showing the cyst cavernous space with RBC (H&E stain, 10x)

Figure 7

Postoperative radiograph

The histopathological examination of the surgical specimen revealed capsule of a cystic lesion with many dilated blood filled cavernous spaces and extravasated RBCs. These spaces were separated by fibrous septa with osteoid tissues, multinucleated giant cells and macrophages [Figure 8]. The diagnosis of an aneurysmal bone cyst was made.

Figure 8

Postoperative photograph

The patient had a good postoperative recovery, with good healing. He was on constant follow up for 12 months without any signs of local recurrence. Patient is yet to be dentally rehabilitated on the affected site.

DISCUSSION

Aneurysmal bone cyst was first described by Jaffe and Lichtenstein in 1942 and was subsequently further defined by both of these authors and became known as Jaffe-Lichtenstein disease.[1-3] The term aneurysmal seems to relate to the blow out distension and the word cyst relates to the fact that the tumor often presents as a blood filled cavity.[3]

Aneurysmal bone cyst is an uncommon lesion which has been found to occur mostly in long bones of the skeleton, and the spine.[4-6]

The first reported case of aneurysmal bone cyst involiving the craniofacial skeleton was reported by Bernier and Bhaskar[7] (1958). Since 1984 only 60-70 cases have been reported. Struthers and Shear have found the peak incidence in the second decade, with slight predilection for females. Most of the reported cases were located in the molar region of the mandible involving the angle and ascending ramus.[5]

Aneurysmal bone cyst produces firm swellings which is rarely associated with pain.[58] The swelling and malocclusion becomes progressively worst, and the rate of enlargement is often rapid. Occasionally, there will be displacement of teeth and resorption of roots of adjacent teeth but none of this was evident in our case except for rapid growth. When the lesion perforates the cortex and it is either covered by periosteum or only a thin shell of bone and may exhibit egg shell crackling, but no pulsations or bruits are heard. Trauma does not seem to have a significant role.

Radiographically these lesions are usually unilocular,[89] but long standing lesions may show a “soap-bubble” appearance and may become progressively calcified. Radiographic, differentiation from other expansile lesions may be difficult. CT scan and MRI may not provide clear diagnostic criteria but only outline the extent of the lesion.[1011] This is because of the similarity of radiographic picture of these lesions to eosinophilic granuloma, giant cell tumor, non ossifying fibroma, Ewing's tumor, and in older patient metastatic carcinoma or myeloma.

A biopsy is often helpful, but needle biopsy is sometimes a problem because of the material obtained may consists of mostly blood elements. An incisional biopsy and frozen section are more reliable.[12]

There is no uniform strategy on treatment and management of these lesions due to its varied nature.[11] The usual treatment of choice is curettage as it is a benign lesion. But there is high recurrence rate (20-30%) reported in various studies.[91113] Other modalities of treatment have been tried, curettage followed by implantation with allograft chips, polymethyl methacrylate, autografts, cryotherapy, local injections of steroids, radiation therapy (Mega voltage, 26-30 Gy), injecting fibrosing agents, demineralized bone powder mixed with bone marrow aspirate introduced into the cyst to halt the expansion phase and to allow the cyst to ossify, segmental resection with use of rhBMP2 along with the rib graft has also given good results.[14] Segmental resection with immediate bone grafting with vascularised bone graft is suggested for extensive lesions such as the present case where a vascularised fibula flap was used to reconstruct the defect.[1113] If untreated, such lesions can lead to pathological fracture and cosmetic deformities. Preoperative transcutaneous intralesional embolization has been tried recently prior to resection to produce a bloodless field.[6]

The term giant aneurysmal bone cyst is very rare and further diagnostic criteria need to be established.[1511]

CONCLUSION

Aneurysmal bone cyst still remains an enigma, not only regarding causation, but also regarding clinical diagnosis, imaging, and optimal treatment. Recently some markers have been identified which are specific for aneurysmal bone cyst. There is still no reliable system which would establish diagnosis, support and define different treatment modalities so as to eliminate the problems encountered both by the patient and the surgeon.