Fig. 2: Representative histological images of HMGA2-NCOR2 fusion-positive giant cell tumors.

At low-power, the subcutaneous tumor is well circumscribed with vague lobulation and a central zone of ischemic-type necrosis (A). Variable lobulation is seen (B). Pericapsular lymphoid aggregates are consistent findings (C). D Higher magnification of the ischemic-type necrosis. E Cellular areas with pseudoangiomatous or aneurysmal stromal changes. F Numerous multinucleated osteoclast-type giant cells are evenly distributed among the mononuclear bland cell component.