The pathogenesis, cell origin, nomenclature, and clinical behavior of aneurysmal bone lesions have been discussed since the first appearance of an aneurysmal bone cyst (ABC). The aim of the present study was to investigate the origins of the different cells constituting aneurysmal bone lesions and to explain the different clinical behaviors of these lesions.
METHODS
In the present investigation, the study group consisted of 30 cases of primary ABC, 24 cases of solid or
aggressive aneurysmal bone cyst (SABC), and one case of aneurysmal bone cyst with nuclear pleomorphism
(ABCNP) that are aneurysmal bone lesions (ABL) showing different biological behaviors. A cell
origin study was performed with Factor VIII-related antigen (RAG), CD 34, and CD 68 antibodies. To
show cell proliferations and evaluate the biological behavior of ABLs, AgNOR counts and immunohistochemical
staining methods with Ki67 and MDM2 were applied.
RESULTS
Our results suggest that the sinusoidal lining cells developed as a result of mesodermal cells differentiating
by different methods. The mononuclear cells of the lesions were found to be mesenchymal cells
with histiocytic characteristics, which was consistent with the literature. The proliferation rate of SABCs
were determined to be higher than those of ABCs, considering AgNOR counts, Ki67 proliferation index,
and MDM2 results.
CONCLUSION
All our findings show that SABC has a higher proliferative potential and more aggressive biological
behavior. It is possible to consider SABC as a subgroup of ABC, a benign tumor. The question of there is
a malignant form of benign ABC still needs to be investigated further.