Aneurysmal bone cyst of maxillary alveolus: A rare case report.

Aneurysmal bone cyst (ABC) is a nonneoplastic rare pathologic entity of the jaws. Its locally aggressive nature and high recurrence rate after curettage make surgical resection a better treatment option. Here, we present a case of ABC of maxillary alveolus and its management by alveolectomy followed by white head varnish pack application in the surgical defect.

Introduction

Aneurysmal bone cyst (ABC) as defined by the World Health Organization is an expansive osteolytic lesion consisting of blood-filed spaces and channels divided by connective tissue septa that can contain osteoid tissue and osteoclast-like giant cells. Although Jaffe and Lichtenstein coined the term “aneurysmal bone cyst” in 1942, it is not lined by epithelium and is not a true cyst. ABC most commonly occurs in long bones and only 2% occur in the jaws. Available literature suggests that the mandible is affected more frequently than the maxilla, the proportions varying from 2:l to 11:9. We report a rare case of ABC of maxillary alveolus.

Case Report

An 8-year-old male reported with the complaint of right upper gum swelling for 2 months associated with dull pain and bleeding. The patient's guardian presented a history of trauma to the face due to accidental fall while playing.

Extraorally, there was a diffuse swelling of right mid face with obliterated nasolabial fold [Figure 1a]. Intraorally, the swelling was of 3 cm × 2 cm in size, extending between 11 and 55 with expansion of both palatal and buccal cortex [Figure 1b]. The soft tissue mass was reddish and firm consistency. There was mild tenderness on palpation and blood on aspiration.

Figure 1

(a and b) Clinical presentation of the aneurysmal bone cyst

Contrast-enhanced computed tomography showed a well-defined multiseptated expansile cystic lesion of right upper alveolus with thin out and resorption of remaining maxillary bony cortex and heterogenous enhancement in postcontrast images suggestive of ABC [Figure 2].

Figure 2

(a and b) Computed tomography shows multiseptated expansile cystic lesion of right maxillary alveolus

Histopathology report showed cavernous vascular spaces filled with blood and surrounded by fibro-collagenous tissue. There were multinucleate giant cells at places and reactive new bone formation at certain areas of the wall. The features were consistent with ABC [Figure 3].

Figure 3

Cavernous vascular spaces filled with blood and surrounded by fibro-collagenous tissue with multinucleate giant cells at places and reactive new bone formation

Surgical resection was carried out of the involved alveolar portion and the gingival soft tissue growth [Figure 4a]. White head varnish pack was secured with suture in the defect [Figure 4b]. It healed uneventfully with complete epithelialization. The child is still under our regular follow-up and there is no clinical evidence of recurrence [Figure 5].

Figure 4

(a and b) Surgical resection of the alveolar portion followed by application of white head varnish pack in the defect

Figure 5

1-year postoperative view

Discussion

ABCs are divided into primary and secondary categories, depending on the presence or absence of other preexisting entities. The pathogenesis of ABC is still controversial. The role of trauma has been suggested by few authors.[1] Some authors favored intra medullary hematoma as the cause of ABC.[2] Local circulatory abnormalities leading to increased venous pressure and resulting in dilation of the local vascular network is one of the most widely accepted theories available in literature.[3] Recently, chromosomal translocation t (16;17)(q22;p13) as a recurrent cytogenetic abnormality has also been suggested as a responsible factor for primary ABCs.[4]

Clinically, ABCs are variable in their mode of presentation from asymptomatic lesions discovered as radiolucencies on routine radiography to expansile destructive patterns.[5] A painless swelling is suggested as the main symptom by some authors.[3] Loosening or displacement of teeth, nasal obstruction, and lip paresthesia are other associated symptoms.[5]

Hemorrhage can occur, especially if the alveolar bone is involved.[6] Only one pathologic fracture has been reported due to ABC of the jaw.[7] Aspiration of a dark red or brownish hemorrhagic fluid is suggestive of ABC.

Radiographic features can be suggestive, but not diagnostic for ABC. It may appear as unilocular or multilocular, expansive, osteolytic radiolucent lesion, with expansion and thinning of the surrounding cortical bone.[8]

Histologically, ABC consists of numerous blood-filed sinusoids surrounded by variable amount of fibrous connective tissue stroma containing multinucleated osteoclast-like giant cells adjacent to sinusoidal spaces, inflamatory cells, extravasated erythrocytes, and hemosiderin.[8] There may be osteoblasts and woven osteoid bone within the connective tissue stroma.[9] Three types of ABC are described based on histopathological features.[9] A dense stroma, scanty sinusoids, few blood vessels and caverns, bone expansion (instead of perforation), and without severe bleeding during surgery are characteristic of solid type (5% of the cases). A loose scanty stroma, numerous engorged blood-filed sinusoids, and caverns are features of vascular variant (95% of cases). Bleeding might be encountered during surgery and extensive bony destruction with spread in the soft tissues is also obvious. The mixed type is the combination of the two previous variants.[9] Our case was of vascular type as bony destruction and growth of the lesion to gingival tissue were evident.

Surgical therapy is the most frequently applied treatment of ABCs,[6] although embolization, cryotherapy, and wait and see strategy have also been used as other treatment modalities.[10]

The size and position of the lesion determine the extent of surgery, ranging from simple curettage to extended resection.[6] ABCs have a high recurrence rate and usually recur within the 1st year after the initial treatment. Reported recurrence rates after surgical curettage and resection of ABCs long bones are 20–70% and 11–25%, respectively.[3]

Study on ABCs of the jaws revealed that 76.5% of ABCs are combined with another pathologic entity, such as ossifying fibroma, central giant cell granuloma, or benign osteoblastoma.[6] They thus suggested dominance of secondary ABCs over primary ABCs within jaws, so curettage may not be an appropriate treatment of ABCs of the jaws.[6] Considering the aggressive nature of the lesion and age of the patient, a conservative surgical resection of the involved alveolar portion was carried out. There was no incidence of excessive bleeding during the surgery.

Conclusion

ABC is a rare pathologic entity of jaws. Primary ABCs of maxilla are rarer. Incisional biopsy and aspiration may help in a definitive diagnosis over its confusing clinical and radiological features, which are similar to various other pathologic entities of the jaws. Conservative surgical resection is preferable to curettage as the latter is associated with much higher rate of recurrence.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.