Musculoskeletal bone, CT, MR, Plain radiographic studies, Education, eLearning, Education and training, Inflammation
M. N. Byrdy-Daca, P. D. Palczewski, M. Duczkowski, J. Świątkowski, K. Piłat, K. Błasińska, I. Sudoł-Szopińska, M. Gołębiowski
Chronic recurrent multifocal osteomyelitis (CRMO) as a type or another designation of CNO (chronic non-bacterial osteomyelitis) is a rare aseptic inflammatory disorder that primarily affects children and adolescents, with prevalence ranging from 1:160,000 to 1:2,000,000 . CRMO is considered to be the paediatric form of the adult SAPHO syndrome, which stands for synovitis, acne, pustulosis, hyperostosis, and osteitis .
It is believed that CRMO/SAPHO are induced by Propionibacterium acnes infection, which in genetically predisposed individuals results in an impaired immune reaction with overproduction of IL-1β. Recent advances in acne research suggest that first steps of this disorder are driven by a relative deficiency of FoxO1 within the nucleus of sebaceous and bone cells . The result is a culture-negative, autoinflammatory involvement of the bones, joints, and entheses.
The onset of the disease is insidious with nonspecific general symptoms such as fatigue, weight loss, fever, as well as local pain, swelling, and limited mobility. Laboratory test results are typically unremarkable with ESR and CRP normal or only slightly raised. Patients usually present with single-site ailments, but subsequently other affected areas are revealed by imaging studies or appear during the course of the disease. In adults, the course of disease is usually slower with less progression. There is an overall significant delay in diagnosis of about 1 year, in part due to the fact that the initial diagnosis is frequently mistakenly led towards bacterial inflammation or neoplastic disease.
The diagnosis CRMO is usually based on criteria by Jansson et al. or Bristol criteria, and the diagnosis of SAPHO is usually based on criteria by Benhamou et al. supported by criteria proposed by Kahn on ACR 67th Annual Scientific Meeting in 2003. (tbl 4 and 5)
This pictorial review was based on a group of 45 patients with SAPHO/CRMO diagnosed and followed up in five Polish hospitals. Considering the rarity of SAPHO/CRMO, we decided to present key imaging features of this disorder, in the hope of creating a useful aid for its imaging diagnosis.