A simple bone cyst (SBC) is typically seen in the diaphysis of the immature skeleton, showing a well-defined osteolytic lesion, mildly expansile with a narrow zone of transition (FIg. 1). The humerus is the commonest site involved, followed by the femoral neck-shaft junction.
Uncomplicated SBCs or unicameral bone cysts, as they are often called, are easy to diagnose. With fracture and hemorrhage, the appearance may occasionally be confusing. Though they may be treated by surgery, they can also be treated by image-guided intra-lesional steroid injection.