Osteosarcoma

Osteosarcoma involving proximal femur. Note the immature epiphyseal plate which acts as a relative barrier to the tumor in this case. The tumor, however, has breached the cortex producing a bulky soft tissue mass with areas of aneurysmal bone cyst formation, telangiectasis, hemorrhage, and necrosis. Image courtesy of Dr. Jean-Christophe Fournet, Paris, France; humpath.com; Used with permission