Autosomal dominant osteopetrosis is the less severe type of osteopetrosis and should be considered and compared with the other subtype autosomal recessive osteopetrosis. The autosomal dominant (AD) type is less severe than its autosomal recessive (AR) mate. Hence, it is also given the name "benign" or "adult" since patients survive into adulthood (something that is unlikely with the AR-type).
- multiple fractures
- multiple cranial nerve compression: e.g. leading to deafness and/or blindness
- hepatosplenomegaly: from extramedullary hematopoiesis due to bone red marrow replacement
In all osteopetrosis (whether AD or AR) there is a deficiency of osteoclast function and the result is that bone becomes dense. However, their altered internal architecture renders them weak. Therefore, patients have dense, sclerotic, fragile bones that fracture easily.
- type I: pronounced osteosclerosis of cranial vault with clinical presentation as cranial nerve palsies
- type II: end plate thickening of vertebrae (sandwich vertebra) and endobones ("bone-within-bone" appearance) in the pelvis, increased risk of fracture
- bone within a bone appearance (see case 1): one of the classical appearances of autosomal dominant osteopetrosis
- Erlenmeyer flask type deformity of the tubular bones
- sandwich vertebrae: diffuse endplate sclerosis (peripheral bony sclerosis) and lucency of the center of vertebral body
- alternating radiolucent metaphyseal bands
Treatment and prognosis
Treatment is with bone marrow transplant and resultant normalization of bone production. Prognosis for the AD adult subtype is good with a reasonable life expectancy.
General imaging differential considerations include:
- autosomal recessive osteopetrosis
- heavy metal poisoning (e.g. lead)
- hypervitaminosis D
- renal osteodystrophy
- fibrous dysplasia of skull or face