[Aneurysmal bone cyst or giant cell tumor. The value of x-ray diagnosis for differential diagnosis].

Depending on analysis of radiographic morphology, location and patient's age of 72 aneurysmal bone cysts (ABC) and 47 giant cell tumours (GCT), the following criteria suggest an ABC with a high positive predictive value: location in the diaphysis (100%), in the shaft (92%), in the metaphysis or metadiaphysis (86%), patient younger than 17 years (97%) and growth rate grade Lodwick-IA (88%). GCT were selected via the following criteria: epimetaphyseal location (82%) and growth rate grade Lodwick-II (100%). In 14% of the cases, differential diagnosis between both entities is radiologically impossible.