Synovial hyperemia in giant cell tumor of bone: angiographic pitfall

Arteriography has been found useful in the clinical staging of giant cell tumors of bone in its capacity to demonstrate the presence and extent of soft tissue, extraosseous extension of the tumor. A potential source of error is the presence of hyperemic synovial tissue that may closely resemble tumor vascularity, and therefore be confused with tumor extraosseous extension. Of the 48 giant cell tumors in this series, 21 demonstrated extraosseous vascularity representing synovial hyperemia. Two patients were considered to have extraosseous tumor extent but only hypertrophic synovial tissue was found at surgery. The angiographic features of synovial hyperemia are outlined.