Aneurysmal bone cyst: a review

Abstract

Aneurysmal bone cyst (ABC) is a benign locally destructive bone neoplasm composed of multi-loculated blood-filled cystic spaces. The most common sites of involvement are the meta-diaphysis of the long bones and posterior elements of the vertebrae. Secondary, ABC-like changes can complicate a variety of other benign and malignant primary bone neoplasms, including giant cell tumor, fibrous dysplasia, and osteosarcoma. About two-third of primary ABCs have a rearrangement of the USP6 gene, which is not present in the ABC-like changes that occur secondary to other primary bone tumors (i.e., secondary ABC). Primary ABC of bone carries a variable but generally high rate of local recurrence. This paper provides an overview of the pathophysiology, clinical presentation, radiographic and pathologic findings, treatment, and prognosis of ABC.

Keywords: Aneurysmal bone cyst; Bone cyst; USP6 gene.

Fig. 1.

Plain radiography of aneurysmal bone cyst. (A) X-ray demonstrates a lytic lesion in the proximal metaphysis of the tibia with slight expansile features and lucency extending through the cortex. (B) X-ray shows an expansile lucent lesion centered in the medullary cavity of the proximal humeral metaphysis with cortical thinning. (C) X-ray shows an eccentric lucent lesion of the medial side of the distal tibia. (D) X-ray shows an expansile multiloculated lucent lesion of the calcaneus.

Fig. 2.

Computed tomography (CT) and magnetic resonance imaging (MRI) of aneurysmal bone cyst. (A) CT scan shows a well-demarcated ovoid area of lucency within the medial aspect of the distal tibia. (B, C) MRI shows an expansile well-demarcated cystic lesion of the proximal tibia with fluid-fluid levels. (D) Sagittal view T2 MRI demonstrates multiple fluid-fluid levels of the cyst involving the calcaneus bone.

Fig. 3.

Gross findings of aneurysmal bone cyst (ABC). (A) ABC involving the distal fibula, showing an expansile lesion with multiple bloodfilled cystic spaces. (B) ABC involving tibia, showing an expansile lesion with multiple blood-filled cystic spaces.

Fig. 4.

Frozen section findings of aneurysmal bone cyst. (A) Frozen section of a multiloculated cystic lesion of the distal tibia. Cystic space with flat attenuated lining and increased stromal giant cells. (B) The solid area shows scattered giant cells in the background of fibrovascular stroma. Cellular atypia is not present.

Fig. 5.

Histologic features of aneurysmal bone cyst. (A) Irregular cystic spaces with multi-nucleated giant cells are present. (B) Multiple irregular cystic spaces, some filled with blood, and a variable number of giant cells in the cyst wall. (C) Blood-filled cystic spaces with cellular giant cell-rich cyst wall. (D) Cystic spaces and portion of cyst wall with scattered giant cells. No significant atypia is present.

Fig. 6.

Blue reticulated chondroid-like material. (A, B) Cyst wall with “blue reticulated chondroid-like material” and hemosiderin deposition.