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What is Chronic Recurrent Multifocal Osteomyelitis (CRMO)?
CRMO has been described in more than three decades as an autoinflammatory, non-malignant disease that affects the bones of mostly young female children. It is a severe but rare disease that is not quite easy to diagnose because of the following features:
- It affects mostly female children, around the ages of 9-14, but has been diagnosed even in the very young (6 months old) and in adults more than 50 years of age.
- There are no known causes of the disease, except that it has been associated with genetic mutations.
- It is an inflammatory condition of the bones, but there are no particular bacteria or viruses that can be identified to cause the disease. Furthermore, it does not respond to antibiotics; instead, steroids have been effectively used to suppress it.
- It is usually associated with other inflammatory conditions like acne, psoriasis and inflammatory bowel disease.
- Only a single bone site may be symptomatic, although many (multifocal) bones may be affected. The symptomatic site may have negative radiologic finding, but whole body analysis may reveal the presence of other bone involvement.
- It mimics other diseases of the bone, such as bacterial osteomyelitis, osteosarcomas (cancer of the bone), leukemia, and bone metastasis. It is often diagnosed by exclusion rather than by direct identification and analysis.
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Clinical Presentation of CRMO
Chronic recurrent multifocal osteomyelitis often presents as bone pain that is deep and aching, swelling, limping, limitation in motion, with or without fever. Onset may be vague and the duration of the symptoms may occur for a few days or even years. It follows a chronic, recurring and relapsing course.
Bones commonly affected include the long bones of the extremities (arms and legs), the clavicle (collar bone) and the shoulder. The pelvis, spine, ankle and foot may also be involved. Usually only one site is symptomatic but as many as 18 sites have been reported.
Skin manifestations have been reported, such as acne and pustules (blister-like lesions with pus) in the palms and soles. Others have inflammatory bowel disease or uveitis (inflammation of the eye).
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Diagnosis of CRMO
This disease is difficult to diagnose, and it will often need a team of doctors, composed of a pediatrician, an orthopedic surgeon, a radiologist and a pathologist to make a complete evaluation. Diagnosis is often by exclusion of other bone diseases that it mimics, because initial history, physical examination and laboratory work-ups show non-specific results pointing to an inflammatory process.
Blood studies show signs of inflammation, such as increased erythrocyte sedimentation rate and C-reactive protein level with a normal white blood cell count.
Bone biopsy reveals inflammatory changes without signs of bacterial infection.
Radiological evaluation usually presents multifocal bone involvement. Inflammation and osteolytic lesions or evidences of bone destruction are observed, but these are similar to other diseases and not characteristic of CRMO alone. Although the tibia (leg bone) is the most commonly involved site, many other bones are most likely to be found positive for changes like the hip bones, shoulder and collar bones, and even the mandible and ribs. X-rays, bone scans, CT scans and MRI are useful in evaluating bone changes and progression of the disease.
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Treatment and Prognosis of CRMO
Mainstay of therapy is the use of non-steroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen. Antibiotics are not necessary. If NSAIDs are not effective, steroids and other immunosuppressants may be used. Other drugs that have been used are methotrexate, interferon and tumor necrosis factor. Surgery is not advisable.
In young children bones may return to normal as evidenced radiologically, but in some adults residual bony deformations may occur. When long bones are involved, bony overgrowths, discrepancies in limb length and angular deformities might develop. In children growth arrest may occur. Pathologic fractures may also be a complication.
The course of the disease is variable and unpredictable. Patients usually undergo spontaneous resolution, but symptoms may last from a few months to many years. In general, prognosis is usually good with no resulting physical impairments.
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Radiographics, “Imaging of Chronic Recurrent Multifocal Osteomyelitis" accessed 12/04/10
Bone tumor.org, “Chronic Recurrent Multifocal Osteomyelitis (CRMO)" accessed 12/04/10