Aneurysmal Bone Cysts
Aneurysmal bone cysts are benign primary or secondary lesions that are rapidly expansive and locally destructive. They are located in the posterior elements of the vertebral column or the flat or long bones of patients under 30 years of age. The cysts are blood-filled and separated by septa containing spindle cells, trabeculae of bone, and osteoclastic giant cells (Biesecker et al., 1970). Histopathologically and radiographically, aneurysmal bone cysts are similar to telangiectactic osteosarcoma from which they must be differentiated. Panoutsakopoulos et al. (1999) described 3 cases of aneurysmal bone cysts with chromosomal anomalies; 16q22 was involved in all 3 patients and 2 of them had a recurrent t(16;17)(q22;p13). Herens et al. (2001) reported 2 additional cases of aneurysmal bone cysts with a t(16;17)(q22;p13). One patient was a 7-year-old girl who was admitted to hospital because of pain in the hip and left knee, and an expansile lytic lesion of the L5 vertebra involving the posterior arch and destroying the lateral pedicles was found. The second patient was a 5-year-old girl with an expansive mass in the occipital region of the skull. The findings in these patients suggested alteration of genes in 16q22 and/or 17p13.