Ivory vertebra | Radiology Signs

The ivory vertebra sign refers to diffuse homogeneous sclerosis of a vertebral body on a plain radiograph or CT scan, retaining normal size and shape without involvement of adjacent intervertebral discs. This radiological sign is seen primarily in pathologies that provoke an osteoblastic or sclerotic reaction within the vertebral trabeculae.

Common clinical conditions include:

• Osteoblastic metastases, especially from prostate carcinoma
• Lymphomatous infiltration (most often Hodgkin lymphoma)
• Paget’s disease of bone

Less common causes include infectious spondylitis or primary bone sarcomas. The sclerosis arises due to increased bone formation or altered bone remodeling within the vertebral trabeculae.

Why is it called so?

The term “ivory vertebra” is derived from the vertebral body’s appearance on imaging, where it becomes uniformly dense, smooth, and white resembling polished ivory. This striking homogeneous whiteness contrasts with the normal trabecular pattern of other vertebrae, prompting the descriptive name.

Pathophysiology

The pathophysiologic basis involves replacement or remodeling of the vascularized trabecular bone in the vertebral body by dense, sclerotic bone tissue. In metastatic disease and lymphoma, osteoblastic stimulation leads to confluent new bone deposition and sclerosis of the vertebral spongiosa. Paget’s disease causes cortical thickening and coarsening of trabeculae with simultaneous spongiosa atrophy, producing a similar radiodense appearance. The increased bone density increases X-ray attenuation, causing the vertebra to appear homogeneously opaque without changes in vertebral height or shape.