Figure 3From: Uncommon cause for anterior knee pain - Aggressive aneurysmal bone cyst of the patella Histology sample. Histology sample showing a typical picture of aneurysmal bone cyst. Hematoxyline-Eosine stain, 20×. Cavernomatous spaces lined with endothelial cells and containing extravasated red blood cells. Note the multinucleated giant cells.Back to article page