A Historical, Histogenetic, and Proliferative Approach to Aneurysmal Bone Cyst

Abstract

OBJECTIVEThe pathogenesis, cell origin, nomenclature, and clinical behavior of aneurysmal bone lesions have beendiscussed since the first appearance of an aneurysmal bone cyst (ABC). The aim of the present study wasto investigate the origins of the different cells constituting aneurysmal bone lesions and to explain thedifferent clinical behaviors of these lesions.METHODSIn the present investigation, the study group consisted of 30 cases of primary ABC, 24 cases of solid oraggressive 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 cellorigin study was performed with Factor VIII-related antigen (RAG), CD 34, and CD 68 antibodies. Toshow cell proliferations and evaluate the biological behavior of ABLs, AgNOR counts and immunohistochemical staining methods with Ki67 and MDM2 were applied.RESULTSOur 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 cellswith histiocytic characteristics, which was consistent with the literature. The proliferation rate of SABCswere determined to be higher than those of ABCs, considering AgNOR counts, Ki67 proliferation index,and MDM2 results.CONCLUSIONAll our findings show that SABC has a higher proliferative potential and more aggressive biologicalbehavior. It is possible to consider SABC as a subgroup of ABC, a benign tumor. The question of there isa malignant form of benign ABC still needs to be investigated further.