Chronic Recurrent Multifocal Osteomyelitis - Search for a Bacterial Cause and Improving Imaging With PET/MRI

Epidemiology, clinical manifestations and prognosis Chronic recurrent multifocal osteomyelitis (CRMO) is an immune-mediated chronic inflammatory self- limiting disease with non-suppurative inflammation involving one or multiple bone foci. The disease occurs primarily in children and adolescents. The estimated prevalence is 1-5/10.000 in the European population, but since there are no studies providing precise estimates, the number of cases can be both under- and overestimated.

The mean age of CRMO onset is 10 years. There is a female preponderance with twice as many girls affected.

CRMO presents with bone pain with or without swelling and warmth. Some patients have a more acute presentation with severe pain, malaise and fever. All bones except the neurocranium can be affected. Involvement of the clavicle is classical, but the metaphyses of the long bones, the mandible and the pelvis are also frequently affected. Vertebral involvement is seen in 4 to 30% of cases in retrospective studies.

Extra-skeletal involvement can include the skin, the eyes and the gastrointestinal tract. Involvement of the skin may manifest as plantar pustulosis, psoriasis acne, pyoderma gangrenosum and Sweet Syndrome. In the gastrointestinal tract, Crohn's disease or lesions mimicking this disease have been associated with CRMO.

Previously, the prognosis of CRMO patients was considered favorable, as the disease is often self-limiting, but newer studies have revealed that physical impairment may persist in up to 50% of patients. They typically suffer from chronic pain, bone deformities and have increased fracture risk. Furthermore, there is evidence that CRMO may evolve into spondyloarthropathy with clinical and radiological sacroiliitis.