Hereditary multiple exostoses
Hereditary multiple exostoses, also known as diaphyseal aclasis or osteochondromatosis is an autosomal dominant condition, characterized by the development of multiple osteochondromas.
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Epidemiology
Hereditary multiple exostoses demonstrate an autosomal dominant inheritance pattern, with incomplete penetrance in females. The number of exostoses, the degree, and type of angular deformity, and even the rate of malignant transformation varies significantly, even within families.
Clinical presentation
Most patients are diagnosed by the age of 5 years, and virtually all are diagnosed by the age of 12 years. Patients may be asymptomatic with a few small lesions or may be significantly deformed by multiple large osteochondromas.
Radiographic features
Except that they are multiple, imaging features are identical to solitary osteochondromas. The skeletal distribution of lesions can significantly vary, with some authors noting that the typical distribution is bilateral and symmetric, whereas others report a strong unilateral predominance.
Often associated with a broadened shaft at the end of long bones, hence the term diaphyseal aclasis.
Complications
Are also similar or those of solitary osteochondroma and include:
- vascular impingement
- neural impingement
- fracture
- bursitis
- deformity and ankylosis
- malignant transformation
Malignant transformation is more common than in sporadic cases, with transformation rates reported as high as 25% (lower rates of 3-5% have also been published) 3. The mnemonic GLAD PAST 1 lists the associations with sarcomatous transformation.
Refer to the generic osteochondroma article for more information.
See also
Related Radiopaedia articles
Bone tumours
The differential diagnosis for bone tumors is dependent on the age of the patient, with a very different set of differentials for the pediatric patient.
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bone tumors
- bone-forming tumors
- cartilage-forming tumors
- fibrous bone lesions
- bone marrow tumors
- other bone tumors or tumor-like lesions
- adamantinoma
- aneurysmal bone cyst
- benign fibrous histiocytoma
- chordoma
- giant cell tumor of bone
- Gorham massive osteolysis
- hemangioendothelioma
- haemophilic pseudotumor
- intradiploic epidermoid cyst
- intraosseous lipoma
- musculoskeletal angiosarcoma
- musculoskeletal hemangiopericytoma
- primary intraosseous hemangioma
- post-traumatic cystic bone lesion
- simple bone cyst
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skeletal metastases
- morphology
- location
- impending fracture risk
- staging
- approach
- describing a bone lesion
- differentials