Possible Mechanism for Pathogenesis of Aneurysmal Bone Cyst Degenerated from Intraosseous Lipoma: Case Report and Literature Review

Abstract

Intraosseous lipomas are rare bone tumors, the pathogenesis of which remains controversial. In the involution of lipomas, many conditions were reported, such as fat necrosis, cystic formation, and dystrophic calcifi cation. Moreover, degeneration of an intraosseous lipoma into an aneurysmal bone cyst (ABC) is extremely rare. We report a patient who had coexisting features of an intraosseous lipoma and ABC diagnosed by a radiologist, pathologist, and orthopedic surgeon. No such case has been published, and we propose a possible mechanism according to the most tenable hypothesis. The patient was successfully treated with intralesional curettage and implantation of polymethylmethacrylate. There are a number of hypotheses regarding the etiologic factors for intraosseous lipomas and ABCs. The rare case reported herein may provide some clues about the pathogenesis of these two diseases.