Introduction and Definition:
ABC's may be secondary to an underlying lesion such as non-ossifying fibroma, chondroblastoma, osteoblastoma, UBC, chondromyxoid fibroma and fibrous dysplasia. The lesion should be examined microscopically in several places to eliminate the possibility of a primary lesion. In the author's experience, ABC seems to be a primary lesion. However, we are aware of one case where aneurysmal bone cyst was diagnosed by biopsy and confirmed after curettage. Following this a destructive lesion developed and an osteosarcoma was diagnosed. Caution is advised.
In one report (Kransdorf, Amer J Roentgenol 1995 Mar;164(3):573-80) the authors state that the original lesion can be identified in one-third of cases. The most common precursor lesion was giant cell tumor, (19-39%) of cases, followed by osteoblastoma, angioma, and chondroblastoma. Less common precursor lesions were fibrous dysplasia, non-ossifying fibroma, chondromyxoid fibroma, unicameral bone cyst, fibrous histiocytoma, eosinoplilic granuloma, and osteosarcoma. A translocation involving the 16q22 and 17p13 chromosomes has been identified in the solid variant and extraosseous forms of aneurysmal bone cyst.