Histopathology. A) Replacement of bone by fibrous tissue with variable amount of collagen deposition and vascularity. (H&E, 10X objective) B) Presence of marked number of thin-walled vessels next to an area of active bone resorption. The blood vessels are predominantly capillaries, but smaller arterioles and venules are also seen. (H&E, 10X objective) C) Bone replacement by dense fibrous tissue with occasional small blood vessels. (H&E, 10X objective) D) Patchy area of chronic inflammatory infiltration with scattered foamy macrophages. (H&E, 40X objective).