Complete resolution and remodeling of chronic recurrent multifocal osteomyelitis on MRI and radiographs

Abstract

Chronic recurrent multifocal osteomyelitis (CRMO) is a rare condition thought to be under-diagnosed, with a true prevalence of more than the 1 in 10,000 estimated. It is a condition that is classically described as polyostotic with a relapsing and remitting course, preferentially affecting the metaphyses of tubular bones in the pediatric population. Lesions have characteristic appearances of cortical hyperostosis and mixed lytic/sclerotic medullary appearances radiographically, with active osteitis and periostitis best seen with fluid-sensitive sequences on magnetic resonance imaging (MRI). There are reports of lesions resolving on follow-up radiographs and MRI scans, but no supporting images. In particular, although the marrow appearances and degree of osteitis have been shown to improve on MRI, complete resolution and remodeling back to normal has never been demonstrated. We present a case of a lesion that has completely healed and remodeled back to normal appearances on both radiographs and MRI, and consider this the standard for the often loosely used terms "normalization" and "resolution". We discuss the implications of this for our understanding of the natural history of CRMO, and how this adds weight to the condition being significantly under-diagnosed. It provides a "gold standard" to be aimed for when assessing treatments for CRMO, and the optimal outcomes that are possible. It also provides further insight into the potential of pediatric bone to recover and remodel when affected by inflammatory conditions.

Evolution of chronic recurrent multifocal osteomyelitis in a child shown by MRI

“…Our case demonstrated the occurrence of CRMO imaging findings in rare sites such as the radius, found in approximately 1%-5% of all lesions [2] , [4] , and the ribs, which are also rarely affected. MRI was fundamental in the follow-up of the outbreaks and in the evolutionary evaluation of this patient, who has shown partial remission.…”

“…Repetitive outbreaks can cause morphostructural deformities due to hyperostosis. But there are also cases of complete remission, especially in skeletally immature children [2] , [4] . Some patients may evolve with sequelae, such as the premature closure of physes, bony deformity, limb-length discrepancy, kyphosis secondary to fracture compression of the vertebral body, and diffuse demineralization, which may predispose patients to fractures [2] , [3] .…”

“…Chronic recurrent multifocal osteomyelitis (CRMO) is a multifocal nonpyogenic skeletal disorder of unknown etiology occurring mainly in children and teenagers, with a male-to-female ratio of 1:2.1 [1] , [2] , [3] and a true estimated prevalence of more than 1 in 10,000 [4] . However, it has been described in infants as young as 6 months and in adults as old as 55 years [2] , [5] .…”

Chronic nonbacterial osteomyelitis — clinical and magnetic resonance imaging features

“…CNO has a protracted course with numerous exacerbations and relapses at new and old sites. It primarily occurs in children and adolescents, with a peak of onset at 7-12 years and a reported incidence of 0.4-10.0/100,000 [1,9,10]. The true incidence is, however, thought to be higher because the findings are nonspecific.…”

Sternocostoclavicular Hyperostosis: Positive Clinical and Radiological Response on Pamidronate

“…In our two cases, we observed a local reduction in bone turnover on scintigraphy in both, with persistent sclerosis in the first, and, remarkably, resolution of sclerosis in the second. For CRMO, full resolution of lesions on MRI in children after both NSAID and pamidronate therapy has been described earlier ( 35 – 37 ), just like for DSO an improvement of structural bone changes after pamidronate therapy has been reported ( 38 , 39 ). A recent randomized study on the effect of pamidronate in CNO patients in general did report significant improvement on radiological disease activity, but not on chronic inflammatory changes ( 40 ).…”