What are the differentials of eccentric expansile lucent lesions with a sclerotic rim and a narrow zone of transition the metaphysis of long bones?
Non-ossifying fibroma, bone infarct, fibrous cortical defect, fibrous dysplasia, bone cyst.
AP and lateral radiographs of the right knee show an eccentric expansile radiolucent geographic lesion with thin sclerotic borders, internal trabeculations and a narrow zone of transition in the distal femoral metaphysis. There is no osteoid or chondroid matrix, cortical destruction, aggressive periosteal reaction or soft tissue component.It extends to the growth plate and there is a modelling deformity of the distal femur.