Trauma is considered the initiating factor in the development of some cysts, in documented cases involving an acute fracture. Local alterations in the blood flow are related to obstructions that are important in the development of an aneurysmal bone cyst.
The lesion generally arises in a pre-existing bone tumor, this is because of the abnormal bones changes in hemodynamics. An aneurysmal bone cyst can arise from a pre-existing chondroblastoma, a chondromyxoid fibroma, an osteoblastoma, a giant cell tumor, or fibrous dysplasia. A giant cell tumor is the most common cause, occurring in 19% to 39% of cases. Less frequently, it results from some malignant tumors, such as osteosarcoma, chondrosarcoma, and hemangioendothelioma.
The tumor can have an occurrence anywhere that there is bone. Approximate percentages by sites are as shown:
The afflicted may have relatively small amounts of pain that will quickly increase in severity over a time period of 6-12 weeks. The skin temperature around the bone may increase, a bony swelling may be evident, and movement may be restricted in adjacent joints.