Fig. 3

Macroscopic and microscopic biopsy findings. (a) Fragile, yellowish-brown tumor tissue was obtained by the biopsy. (b) Pathologically, the tumor comprised mononuclear stromal cells and multinuclear giant cells (original magnification, ×100). (c) The stromal cells showed oval nuclei with fine, uniform chromatin, and nucleoli were frequently found (original magnification, ×200). Many multinucleated giant cells resembling osteoclasts were surrounded by mononuclear cells (arrows)