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)
Contents
Definition
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.
Occurrence
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
Symptoms
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
Diagnosis
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 by follow-up checks 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).
- Normal blood cell numbers (score 13)
- Symmetric changes (lesions) in the skeleton (score 10)
- Lesions more sclerosis at the edges (score 10)
- Normal body temperature / absence of fever (score 9)
- Vertebral, clavicular or sternal lesions (score 8)
- Radiologically detected at least two lesions (score 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):
- Bacterial infection in the skeleton (osteomyelitis) inclusive tuberculosis (tbc) must be excluded
- Antibiotics do not help on CRMO, and bacteria are not detected (reference: Aygun D, 2015)
- Cancer (Ewing sarcoma, Leukemia, Lymphoma, Rhabdomyosarcoma, Neuroblastoma with metastases) must be excluded
- Benign tumors
- Skeletal changes in other conditions
- Schnitzler syndrome
- Chronic, itchy eczema
- Osteonecrosis
- Add-Calve Perthes
- Other
- Osteosclerosis (may be similar to the CRMO repair process)
- Schnitzler syndrome
Treatment
Symptom relief with NSAIDs (Ibux, Naproxen and more) is standard (reference: Jansson A, 2007)
- In more serious cases have Corticosteroids (Prednisolone) and other immunosuppressive treatment like methotrexate been given
- TNF inhibitors (reference: Eleltheriou D, 2010) and or anakinra are more experimental treatment
- Some have a good respons to bisphosphonate (used otherwise against osteoporosis / osteoporosis) and given for a limited period (reference: Hospach T, 2010)
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.
Literature
- Stern S, Ferguson PJ, 2013
- Lyer RS, 2011
- Sato H, 2017 (debut in adulthood)
Auto-inflammatory diseases (BINDEVEVSSYKDOMMER.no)
