CRMO syndrome 4.42/5 (12)

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Cox AJ, PlosOne, 2017: CRMO in metaphysis on knee. X-ray (A) and MR (B). CC BY 4.0

Chronic recurrent multifocal osteomyelitis (CRMO). Chronic Non-bacterial Osteomyelitis (CNO)


CRMO is a non-infectious, rare disease that attacks children, less often among adults. Unknown cause. Leg substance is attacked by rheumatic inflammation in several places ("multifocal"). CRMOs are often classified among them autoinflammatory diseases / Periodic fever syndromes, but any underlying specific gene defect has not yet been found.


CRMO is a rare disease, but the most common auto-inflammatory condition in Central Europe

  • Most often 7-14 years
  • Girls four times more frequently attacked than boys


Periodic, partly severe skeletal pain. Diffuse symptoms help to make the diagnosis often late

  • Posture if a leg is affected
  • Some get swollen over the affected skeletal area
  • Fever


The diagnosis is based on typical symptoms, changes in MRI examination and in the exclusion of similar diseases.

  • Elevated inflammation parameters are present in blood tests, including Erythrocyte sedimentation rate (ESR) and CRP
  • CRMO is suspected after an assessment of radiographs, CT and / or MRI examinations as in the early phase.
    • The images show localized loss of bone substance (lytic bone defects) surrounded by a thin (sclerotic) edge.
    • Typically, the changes are seen in several areas.
    • Later, seals (sclerosis) are seen as signs of a repair process in the same areas
  • MRI, preferably "whole body MRI", is done at follow-up check-ups to reduce X-ray load and for a good overview (reference: Khanna G, 2009)
  • Most often, changes in the joints are detected (metaphyses og epiphyses) of the long bones in the legs (see illustration at the top of the page), arms, collarbones, shoulders and vertebrae
  • Also the jawbone can be affected, but not the skull
  • Tissue sample is applicable to exclude other diseases (see differential diagnoses below)
  • The average age at diagnosis is 10 years, but with a wide range. CRMO is most common among girls (reference: Borzutzky A, 2012)

A scoring system for the diagnosis (reference Wipff J, 2015).

  1. Normal blood cell numbers (score 13)
  2. Symmetrical changes (lesions) in the skeleton (score 10)
  3. Lesions more sclerosis at the edges (score 10)
  4. Normal body temperature / absence of fever (score 9)
  5. Vertebral, clavicular or sternal lesions (score 8)
  6. Radiologically detected at least two lesions (score 7)
  7. CRP at least 10 mg / L (score 6)

Score total (sum) of at least 39 (maximum 63) is considered diagnostic for CRMO

Incorrect diagnosis? (Similar diseases / differential diagnoses):


Symptom relief with NSAIDs (Ibux, Naproxen and more) is standard (reference: Jansson A, 2007)

Medical prognosis / llife expectancy

The outlook is good, although the course can only be characterized by several relapses.

  • Most are healthy 5-6 years after diagnosis.


Auto-inflammatory diseases (

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