Firstly this needs to be differented from a closely related cousin - Unicameral Bone Cyst the best way to do it is a needle biopsy. A unicameral / simple bone cyst would yield yellow or clear fluid. An aneurysmal bone cyst would look like this from the inside so u know what that would yield The idea that one is an eccentric and the other is not, cannot be used to differentiate the two as both would look exactly the same when advanced ( i.e aneurysmal on X ray, making u wonder, how it did not crack this far). The great Robbin's pathology has not alluded to it even remotely. Good attitude...if u don't hav a clue and don't wish to admit, then stay away. I always thought that Rubin's patho was a braver and better book and this is what they have to say. Aneurysmal bone cyst (ABC) is an uncommon, expansive lesion arising within a bone or on its surface. It occurs in children and young adults, with a peak incidence in the second decade. The lesion has been observed at every skeletal site but is most frequent in the long bones and the vertebral column. Pathogenesis The pathogenesis of ABC is controversial. Some cases represent cystic and hemorrhagic transformation of an underlying lesion, most commonly chondroblastoma, osteoblastoma, fibrous dysplasia, giant cell tumor, and osteosarcoma (termed 'secondary ABC'). Other cases of ABC have no detectable associated lesion (termed 'primary ABC'). Rather, primary ABC may be a true neoplasm since they are associated with a recurring chromosomal tranlocation t(16;17)(q22;p13). This translocation fuses the promoter region of the osteoblast cadherin 11 gene (CDH11) on chromosome 16q22 to the coding sequence of the ubiquitin protease (USP6) gene on chromosome 17p13. USP6 is thought to have a role in regulating actin remodeling. However, the possible mechanism of neoplastic transformation by upregulation of USP6 has not been elucidated. So we have a set of differentials for the secondary, which also needs to be ruled in /out.
