title: A small aneurysmal bone cyst restricted to the cortical bone of the femur resembling so-called subperiosteal giant cell tumor or subperiosteal osteoclasia.
abstract: We report a 16-year-old Japanese girl with a cystic lesion restricted to the cortical bone under the periosteum of the diaphysis of the left femur. Roentgenograms showed a long, oval translucent lesion in frontal view and an eccentric erosive lesion in lateral view. Computed tomography showed a distinct intracortical lesion. The lesion, which was excised en bloc, measured 3 x 2 x 2 cm. The outer layer of the cortical bone was eroded eccentrically. From the margin of the eroded bone, thin fragile bony tissue and preserved periosteum extended like the roof of a dome. Multicystic structures, filled with blood, were lined with fibrous granulation and occasional giant cells. Histologically, this lesion falls within the category of aneurysmal bone cyst. However this case is of a rare type, since the lesion was relatively small, and showed a very specific intracortical location, in marked contrast to typical aneurysmal bone cyst. Additionally, this lesion is similar to so-called subperiosteal giant cell tumor or subperiosteal osteoclasia described in the literature.
authors.affiliation: Second Department of Pathology, Akita University School of Medicine, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Okada
authors.forename: H
authors.initials: H
authors.lastname: Masuda
authors.forename: T
authors.initials: T
authors.lastname: Shozawa
authors.forename: M
authors.initials: M
authors.lastname: Arai
mesh_terms: D000293:Adolescent; D001845:Bone Cysts / Q000175:diagnosis / Q000473:pathology*; D001862:Bone Resorption / Q000473:pathology*; D003937:Diagnosis, Differential; D005260:Female; D005269:Femur / Q000473:pathology*; D005870:Giant Cell Tumors / Q000175:diagnosis / Q000473:pathology*; D006801:Humans