Primary aneurysmal bone cyst of the proximal tibia crossing the open physis

An aneurysmal bone cyst (ABC) is a hyperplastic reactive lesion of unknown etiology consisting of cystic cavities containing blood lined by mesenchymal reactive tissue. It occurs more often in females (2:1), usually before the age of 20 years, and most commonly in long bones [1]. The extension of the primary ABC to the epiphysis after crossing the viable physis is an exceptional finding, and very few such cases have been reported in the literature [2-6]. Although uncommon, ABC can cause severe destruction of long bones in children and young adults. The suggested treatment for such aggressive cases ranges from simple curettage to wide resection and structural reconstruction [7, 8]. Here, we report the follow-up for a 10-year-old girl with large, aggressive ABC of the proximal tibia with transphyseal extension to the epiphysis, which was treated with intralesional excision, curettage and bone grafting.