Background/Purpose:

Chronic relapsing multifocal osteomyelitis (CRMO) is a rare autoinflammatory bone condition presenting primarily in children & adolescents. It characteristically affects the epiphysis & metaphysis of long bones & presents with bony pain, local swelling & warmth.

The aim of this study was to collate our centre’s experience of managing patients with CRMO & establish their longer term outcomes.

Methods:

Our Centre provides a tertiary service for adolescents & young adults >13 years. We performed a retrospective case note review of all patients known to our service with a diagnosis of CRMO.

Results:

We identified 17 (10 female) patients with CRMO presenting between 1999 & 2015. The median age of initial symptoms & age of presentation was 12 years. Median follow up duration 4.75 years (range 1-16.5 years).

On review of long term outcomes, several patients evolved into a different disease phenotype: 3 SAPHO (synovitis, acne, pustolosis, hyperostosis, osteitis), 3 ERA (enthesitis related arthritis) & 2 oligoarticular juvenile idiopathic arthritis (OJIA). The clinical phenotype of patients with SAPHO was predominantly multifocal (involving wrists, jaw, ankle & ribs), with one patient having disease of only the sternoclavicular joints. Of the ERA patients, 2 had sacro-iliac & clavicle involvement, 1 had initial femur involvement which has progressed to ERA around the hips. All patients with OJIA had ankle involvement, with 1 developing knee synovitis as well & 1 wrist & shoulder inflammatory arthritis.

Unifocal osteomyelitis was seen in 35% of patients & 65% multifocal as confirmed by whole body MRI. 70.5% patients had recurrent episodes of inflammation, while 29.5% had only one flare & then remitted (either clinical or confirmed with MRI). 15 patients had their diagnosis confirmed with biopsy, 2 did not due to site of disease being close to the growth line (diagnosis based on clinic impression & typical radiographic findings).

Multiple sites of disease have been confirmed in our patients & include lower limbs (70%), upper limbs (35%), clavicle (29.4%), mandible (17.6%) & spine/pelvis (23.5%).

All patients were treated with NSAIDs. During the course of the disease at any point 76% have been on methotrexate; 47% had one pamidronate infusion & 23% more than 1. Other medications include sulfasalazine, azathioprine, risedronate &anti-TNFs.

On last clinic review, 35% of patients have evidence of ongoing active disease

Conclusion:

The perceived wisdom is that CRMO is a self-limiting disease which eventually goes into remission. However our Centre’s experience is that nearly 50% of our patients have a disease which evolves into another systemic autoimmune disease (SAPHO, OJIA or ERA). This is more frequent in those with multifocal CRMO. Previous case series have suggested only 0-30% of patients’ disease evolves. Our findings may be a reflection of our older cohort of patients.

The majority of patients have a recurrent and multifocal disease. The most common site of disease was in the lower limbs. All patients were treated with NSAIDS, a combination of DMARDS, bisphosphonates & biologic agents have been used, which has resulted in remission of disease in the majority of patients.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/longer-term-outcomes-of-chronic-relapsing-multifocal-osteomyelitis-in-a-uk-tertiary-adolescent-and-young-adult-rheumatology-centre/