A. Brief Descriptions：
Most cases older than 19 years at the time of diagnosis.
The distal femur and proximal tibia account for 60% of cases.
Swelling in the region of affected bone with pain.
B. Gross Findings：
Gray-brown to reddish tumor with necrosis and cyst formation
C. Micro Findings：
A uniform pattern of growth on low magnification.
Multinucleated giant cells lie scattered uniformly in a “sea” of mononuclear round to oval cells.
The nuclear of mononucleated cells and those of the multinucleated giant cells are similar in appearance and uniform in their cytological characteristics.
Mitotic figures are present in some mononuclear cells but absent in the giant cells.
Hemorrhage and degeneration are common.
Robbins Pathologic Basis of Disease, 6th ed. P1244-1245.
【 Fig. 155-1 (LP)】Cellular tumor with hemorrhage.
【 Fig. 155-2 (LP)】Numerous multinucleated giant cells lie scattered in a “sea” of mononuclear round to oval cells.
【 Fig. 155-3 (HP