The clinical symptoms of an ABC are usually accidently discovered or may consist of pain and swelling in the affected region and pathological fractures ( complete and incomplete ) can be observed occasionally. In conventional radiography a relatively well-defined osteolytic, expansile lesion with possible blowout of the periosteum and a soap-bubble appearance can be found (4). MRI scanning shows cystic formations with typical fluid-fluid levels due to blood sedimentation (7). Because of the possible rapid growth with local destruction, the literature describes cases of ABCs that mimic malignant bone tumors
Aneurysmal bone cysts (ABCs) are benign, locally destructive growing bone tumors, which were first described in 1942 by Jaffé and Lichtenstein (1). They are most often diagnosed in childhood and early adulthood. The literature reports that ABCs comprise 1-6% of all primary benign bone tumors (2). Most cases of ABCs (75-90%) are reported for patients younger than 20 years, with a slightly higher incidence for females (3). Most common localizations are the pelvis, the metaphysis of long bones and the spine, but ABCs can also affect any other localization(2). ABCs that are associated with a preexisting osseous lesion are defined as secondary ABCs. They represent approximately 30% of all ABCs (2). Secondary ABCs can occur, e.g., in cases of a giant cell tumor, chondroblastoma or telangiectatic osteosarcoma