Intramedullary osteosclerosis is a sclerosing dysplasia associated with increased bone formation within the medullary cavity. It is a diagnosis of exclusion.
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Epidemiology
There is a female predilection, with the condition usually discovered in adulthood. No hereditary risk has been demonstrated.
Clinical presentation
The disorder is usually detected by plain radiography performed following protracted leg pain that may worsen with mechanical loading 1,3.
Pathology
On histology of the medullary cavity, there is a combination of irregular woven bone characterized by crowded bony trabeculae and interspersed lamellar bone.
Radiographic features
The long bones (usually the mid-diaphysis) of the lower extremities are typically affected, with unilateral or bilateral involvement of one or more long bones. The tibia is most commonly affected, but the process may also involve the femur or fibula 1,2. There are no specific radiographic features 3.
Plain radiograph / CT
- osteosclerosis limited to the medullary cavity
- +/- adjacent to the soft tissue swelling
- no cortical thickening nor periosteal reaction
MRI
- homogeneous and continuous sclerosis extending into the medullary canal from endosteal bone +/- obliteration of the canal
- minimal, if any, periosteal cortical thickening
- +/- soft tissue edema/enhancement
Nuclear medicine
Bone scintigraphy
The distribution, as described above, is best demonstrated on bone scan and helps differentiate from other sclerosing dysplasias. Intense uptake is usually demonstrated in the affected regions.
Treatment and prognosis
No treatment is usually required, with supportive management for symptoms as indicated.
Differential diagnosis
Overall, intramedullary osteosclerosis is a rare condition and is a diagnosis of exclusion once other causes of osteosclerosis have been ruled out.
- hereditary multiple diaphyseal sclerosis
- osteomyelitis
- malignancy, metastatic disease
- melorheostosis: classical dripping candle wax sign
- progressive diaphyseal dysplasia
- stress fractures
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