Autosomal dominant osteopetrosis
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 haematopoiesis 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 become dense. However, their altered internal architecture renders them weak. Therefore, patients have dense, sclerotic, fragile bones that fracture easily.
- bone within a bone appearance (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 centre of vertebral body
- alternating radiolucent metaphyseal bands
- 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
Treatment and prognosis
Treatment is with bone marrow transplant and resultant normalisation of bone production. Prognosis for the AD adult subtype is good with a reasonable life expectancy.
General imaging differential considerations include:
- 1. Bollerslev J, Mosekilde L. Autosomal dominant osteopetrosis. Clin. Orthop. Relat. Res. 1993; (294): 45-51. Pubmed citation
- 2. Bénichou OD, Laredo JD, de Vernejoul MC. Type II autosomal dominant osteopetrosis (Albers-Schönberg disease): clinical and radiological manifestations in 42 patients. Bone. 2000;26 (1): 87-93. Pubmed citation
- 3. Kirkland D and O’Brien W. Osteopetrosis – Classic Imaging Findings in the Spine Clin Diagn Res. 2015 Aug; 9(8): TJ01–TJ02.
Metabolic bone disease
- bone mineralisation
- osteosclerosis (differential diagnosis / mnemonic)
- pituitary gland-related
- thyroid gland-related