Chronic Recurrent Multifocal Osteomyelitis or CRMO: Symptoms, Causes, Treatment

Chronic Recurrent Multifocal Osteomyelitis or CRMO, an auto-inflammatory disorder, is characterized by a prolonged and fluctuating course with recurrent episodes of pain occurring over several years.¹ It affects mainly children and young adults. CRMO is most often seen in the clavicle and tubular bones, and less frequently pelvic bones and the spine.

Females are more affected compared to males and half the cases are less than ten years old.² There are variable clinical and radiological features on the disease and it is difficult to diagnose.

To describe this condition, there are multiple names that have been given and are chronic recurrent multifocal osteomyelitis, chronic multifocal osteomyelitis and SAPHO syndrome.

Chronic Recurrent Multifocal Osteomyelitis or CRMO is pathogenetically linked to enthesitis-related arthritis and psoriatic arthritis.³ The intense discussion on the CMRO putative infectious etiology has been postulated to be involved in the pathogenesis especially in Propionibacterium acnes. However, there are no apparent infectious agents that could be detected at the site of bone lesion in pediatric patients. CMRO’s origin and pathogenesis are not entirely clear even though this disease has been recognized as a clinical entity for almost three decades now.

This is a very rare disease and generally is found in children, generally girls. It may also affect adults. Chronic Recurrent Multifocal Osteomyelitis (CRMO) may develop in children ages between 4 and 14. The most common starting point for the development of this condition is age of 10. There have been no epidemiological data on incidence so far. However, the incidence of Chronic Recurrent Multifocal Osteomyelitis (CRMO) might be estimated at 1:1,000,000.

• CRMO damages create characteristic formations known as bone lesions in the affected area of bone. When these lesions flare-up, they cause problems to include aching pain, a pronounced limp, possible constitutional upset, fever, and swelling skin redness.
• The pain may limit the child’s activities and it can be quite severe. Sometimes the child may even require hospitalization. Chronic Recurrent Multifocal Osteomyelitis (CRMO) mainly affects long bone metaphyses and also shoulder girdle and pelvis. The bones that this disease affects more include thighbone, clavicle and shinbone. There are many young people with CRMO that have more than one area of bone pain.

The cause of CMRO is unknown. The possible causes of CMRO include autoimmune reaction (where white blood cells instead of seeking out and destroying foreign invaders turn on the body and attack normal cells instead), infectious disease, and a defect in immune system.

• Adjacent and distal joints arthritis is very frequent. Enthesitis-related arthritis at onset or during the disease course is the feature of Chronic Recurrent Multifocal Osteomyelitis (CRMO).
• Unifocal or multifocal, initially osteolytic, later hyperostotic and sclerotic lesions mainly in long bones metaphyses and shoulder girdle. It also can be affected at any bone. Even under therapy, relapses are frequent.

• Inflammatory bowel disease.
• Uveitis.
• Palmoplantar pustulosis, psoriasis or acne conglobata.

Clinical diagnosis can be difficult in affected children because the course of the disease and clinical picture may vary significantly. This condition can have similar symptoms like arthritis. The person needs to have a series of tests and scans to get a diagnosis.

• Bone Biopsy: Depending on the course of the disease, bone biopsy may show subperiosteal bone formation that is a sign of chronic inflammation with infiltration of leukocytes. Histopathology of bony lesions is the gold standard for diagnosis of Chronic Recurrent Multifocal Osteomyelitis (CRMO). Granulocytes can be observed in very early lesions, and later it show lymphocytes or monocytes.
• Plain Radiographic Findings: Plain radiographic imaging findings can show sclerotic, osteolytic, and a mixed lytic-sclerotic lesion.
• MRI: MRI is an effective diagnostic method and it is very good. MRI can evaluate the activity of lesions and identify the most appropriate site for biopsy.

Still, it is impossible to give effective and definite treatment for CRMO. Treatment aim is to try to treat them if they occur and prevent flareups. To monitor any growth disturbances in the affected bones, it usually requires long term treatment.

• The treatment of choice is nonsteroidal antiinflammatory drugs. Therapeutically, antibiotic treatment is ineffective for Chronic Recurrent Multifocal Osteomyelitis (CRMO) and non steroidal anti-inflammatory agents treatment is effective. Oral steroid treatment, sulfasalazine, and bisphosphonates are generally used and were found to be beneficial.
• Physical Therapy: Physical therapy is advised following complete recovery from inflammatory bone condition to improve muscle function and joint mobility. Physical therapist is avoided during symptoms caused by active inflammatory condition.
• Steroids: Regular doses of steroids are used in severe case of CRMO. It slows down the inflammation and allows the bone to heal. In some specific cases, bisphosphonates, sulfasalazine and oral steroids have also been used.
• Surgical Operations: There are few case reports suggests surgical treatment has helped to improve healing and accomplished rapid anti inflammatory therapy. Surgical treatment is controversial and most specialist advised to avoid surgery.

The long term outcome of CRMO is understood poorly but it may induce bone deformities, psoriasis, inflammatory bowel disease, and school difficulties.

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