Autosomal Dominant Osteopetrosis
A 38-year-old woman whose father and paternal aunts had osteopetrosis presented to a primary care clinic with a 2-month history of progressive back pain. The physical examination was unremarkable. Computed tomography of the thoracic spine (Panels A and B) showed sharply demarcated sclerotic bands on the superior and inferior end plates of all vertebral bodies (arrows) — a finding known as “sandwich vertebrae.” In addition, the presence of sclerotic lines inside the vertebral bodies that were parallel to the anterior and lateral aspects of the vertebral bodies (arrowheads) created a “bone within bone” appearance. No fractures were present. Subsequent genetic testing identified a mutation in the gene CLCN7, and a diagnosis of autosomal dominant osteopetrosis, or Albers-Schönberg’s disease, was made. Osteoclasts in patients with this condition are unable to resorb bone, which causes bone density to increase, primarily in the spine, the pelvis, and the base of the skull. The radiographic findings of sandwich vertebrae and bone within bone strongly suggest the diagnosis and should prompt genetic testing. The patient’s back pain abated with supportive care. During follow-up over a period of 4 years, no compressive neuropathy or fractures developed.