[Diagnostic imaging of giant cell tumors].

Although classified as benign neoplasms, giant cell tumors are locally aggressive with a high recurrence rate of 30-50%. The histological appearance include osteoclast-like, multinucleated giant cells and round to spindle-shaped mono-nuclear stromal cells. These neoplasms predominately affect adults in the third and forth decades of life (70-80%). Giant cell tumors predominately arise in long tubular bones (75-95%) with the majority occurring around the knee (50%). The next most common site being the distal radius (10%). The epicenter of giant cell tumors is in the epiphysis. The radiographic signs of giant cell tumors are a geographical radiolucency with no internal mineralization, a thinning of the cortex, eccentric in the epiphysis of long bones. MRI signs of giant cell tumors are high signal intensity in T2-weighted images, high contrast media enhancement, fluid levels, signs according to haemorrhage and haemosiderin deposition. CT shows the expanded and thinned cortex. Plain radiographs remain the mainstay of diagnosis of giant cell tumors. MRI and CT are important for staging and therefore for surgical planning.