Osteopetrosis, also known as Albers-Schönberg disease or marble bone disease, is an uncommon hereditary disorder that results from defective osteoclasts. Bones become sclerotic and thick, but their abnormal structure actually causes them to be weak and brittle.
There are two separate subtypes of osteopetrosis:
On this page:
Clinical presentation
Presentation, in the majority of cases, is with a fracture due to weakened bones. Fractures are often transverse with multiple areas of callus formation and normal healing.
Additionally, there is crowding of the marrow, so bone marrow function is affected resulting in myelophthisic anemia and extramedullary hematopoiesis with hepatosplenomegaly. This may progress to acute leukemia.
Pathology
Both forms are rare congenital abnormalities with localized chromosomal defects. They result in defective osteoclasts and overgrowth of bone. The bones become thick and sclerotic with disordered architecture, making them brittle. The osteoclasts' lack of carbonic anhydrase leads to an inability to acidify Howship lacunae in bone. Chloride channel dysfunction can also lead to osteopetrosis.
Due to loss of osteoclast activity, the medullary canal of involved bones does not exist; the end of long bones are bulbous and have a characteristic metaphyseal flare (Erlenmeyer flask deformity). The primary spongiosa persist and fill the medullary cavity, leaving no space for hematopoietic tissue, leading to anemia or leukopenia, or/and extramedullary hematopoiesis. Patients may develop cranial nerve compression symptoms like diplopia and weakness of facial muscles. 7
Radiographic features
The features are dependent on the subtype of osteopetrosis and are detailed in the individual articles:
Treatment and prognosis
Treatment is with bone marrow transplant and resultant normalization of bone production. The prognosis for the autosomal dominant adult subtype is good with a normal life expectancy. However, the autosomal recessive infantile subtype can result in stillbirth or death in infancy, with few patients living past middle age.
History and etymology
The term is derived from the Greek words 'osteo' meaning bone and 'petros' meaning stone. It was first described by German radiologist Heinrich Ernst Albers-Schönberg (1865-1921) in 1904 4,6. Interestingly Albers-Schonberg was the first Professor of Radiology in Germany - and perhaps globally - the Chair was bestowed on him by the University of Hamburg in 1919 6.
Differential diagnosis
General imaging differential considerations include:
heavy metal poisoning (e.g. lead)
fibrous dysplasia of skull or face
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