27th February 2025

Sclerosing bone dysplasia

Sclerosing bone dysplasia is a term used to refer to a variety of congenital disorders that range in severity from mild to fatal and in age of onset from childhood to late life, depending on the nature of the genetic abnormality. Cranial nerve palsies can occur in many of these conditions as bone overgrowth narrows cranial foramina, which may cause vision and hearing loss.

In osteopetrosis, general loss of osteoclast function results in a diffuse increase in bone mass, as demonstrated by a ‘marble bone’ appearance on X-ray. Poor remodelling in childhood forms of osteopetrosis result in bone marrow failure due to narrowed marrow cavity. If completed in early life, bone marrow transplantation can provide a cure as osteoclast progenitors are replaced.

Other sclerosing bone dysplasias may affect different parts of the skeleton in unequal ways. These include melorheostosis, which usually affects one limb only, and pyknodysostosis, a lysosomal storage disease affecting osteoclasts, which presents with blue sclera, rhizomelic dwarfism, and osteosclerosis.