Aneurysmal Bone Cyst : Morphology

Comments:
Aneurysmal Bone Cyst (ABC) - Microscopic Features: ABCs are well-circumscribed and composed of variably-sized cystic spaces filled with blood. The cystic spaces lack endothelial lining and are separated by fibrous septa of various thickness.

The septa contain bland fibroblasts, myofibroblasts, hemosiderin-laden and foamy macrophages, and clusters of multinucleated osteoclast-type giant cells. Delicate strands of reactive woven bone lined by osteoblasts are often present in the septa.