Tumour & tumour like: Aneurysmal bone cyst (ABC)

Expansile lytic blood-filled cystic benign lesion, seperated by septae of osteoid and clast cells
Represent a reaction to localized AVM
May occur in association with GCT, FD, CB, hemangiomas
Most common site - metaphysis of long bone
Also less commonly vertebrae, short bones of hands and feet
usually from medullary space, but also subperiosteal region, cortex
Usually first two decades of life, before the fusion of the epiphysis

Expansile, eccentric lucent metaphyseal lesion without epiphyseal involvement
Rarely involves epiphysis
May have aggressive appearance
Cortical thinning, erosion, periostitis may be seen

May show interrupted cortex

Typically well-circumscribed, macrolobulated cystic lesion, containing multiple fluid–fluid levels
The fluid–fluid level is nonspecific and can be seen in FD, SBC, CB

Surgical excision and grafting
Radiation therapy and cryotherapy may be used
Curettage is associated with rapid reccurrence

ABC of rib:
Less than 5% of rib tumours Posterior or posterolateral aspects of ribs

1. Hughes et al. Benign primary tumours of the ribs. Clin rad (2006): 61:314-322