Figure 2.

Osteoclasts and multinucleated foreign-body type giant cells in giant cell tumor of tendon sheath. Left-hand panels show H&E-stained sections of a giant cell tumor of tendon sheath with a mix of collagenous stroma, mononuclear cells and osteoclasts (black arrows) in the lower halves of the images and cholesterol clefts (blue arrows) with multinucleated giant cells (yellow arrows) below an area of necrosis in the tumor in the upper halves. The right-hand panels show low and high power images of the lesion with TRAP-positive osteoclasts and TRAP-negative multinucleated giant cells associated with the cholesterol clefts.