title: Parosteal aneurysmal bone cyst of the humerus with birdcage-like ossification on three-dimensional CT scanning: a case report.
abstract: A rare case of parosteal aneurysmal bone cyst arising from the humerus in a 7-year-old boy is reported. Plain radiography and CT scanning revealed a marked periosteal reaction and a soft tissue mass surrounded by bone. Erosion of the cortex did not extend to involve the medulla. Three-dimensional CT scanning (3-DCT) revealed a birdcage-like ossified structure that was attached to the cortex of the humerus. 3-DCT was also used to visualize the extent of the tumor and the architecture of the bone, providing important information for planning of surgery. Inside the tumor, there were a number of fluid-fluid levels on T1-weighted MRI and high intensity areas on T2-weighted images. Pathologic examination revealed a central cavity containing a large volume of blood in the tumor and reactive osteogenesis mainly at the marginal regions, and these findings reflected the birdcage-like ossified structure observed by 3-DCT. Pathological examination was required to rule out osteosarcoma in particular, but a diagnosis of parosteal aneurysmal bone cyst was made because of the absence of findings suggestive of malignancy. The tumor was excised en bloc with a clear margin. At 3 years after surgery, there is no evidence of recurrent tumor.
authors: Department of Orthopaedics and Rehabilitation Medicine, Faculty of Medical Sciences, The University of Fukui, Shimoaizuki 23, Matsuoka, Fukui, 910-1193, Japan. kshigeru@u-fukui.ac.jp
authors: Shigeru
authors: S
authors: Kobayashi
authors: Katsuhoko
authors: K
authors: Hayakawa
authors: Kenichi
authors: K
authors: Takeno
authors: Hisatoshi
authors: H
authors: Baba
authors: Adam
authors: A
authors: Meir
mesh_terms: D017824:Bone Cysts, Aneurysmal / Q000000981:diagnostic imaging / Q000473:pathology* / Q000601:surgery; D001859:Bone Neoplasms / Q000175:diagnosis; D002648:Child; D003937:Diagnosis, Differential; D006801:Humans; D006811:Humerus / Q000000981:diagnostic imaging / Q000473:pathology; D008297:Male; D009999:Ossification, Heterotopic / Q000473:pathology*; D012516:Osteosarcoma / Q000175:diagnosis; D011859:Radiography; D016896:Treatment Outcome