Intermittent pain, clavicle swelling top key features of chronic nonbacterial osteomyelitis
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An international team of researchers has identified key clinical features of chronic nonbacterial osteomyelitis to help develop vital classification criteria.
“[Chronic nonbacterial osteomyelitis] is very difficult to diagnose because many other diseases can look like CNO, including growing pains, infection or cancer, and it can be very tricky at the beginning of diagnosis so there’s a need for higher standard clinical studies. In order to do that, we need to have well-rounded criteria,” Yongdong Zhao, MD, PhD, RhMSUS, assistant professor and director of ultrasound at Seattle Children’s Hospital and its Center for Clinical and Translational Research, said during a press conference.
According to Zhao, diagnostic criteria have been previously published, but were either from single centers, or did not include mimickers as a control.
“The unique part of our study here, as part of the overall classification criteria development, is to get all the cases together from an international group and include cases that look like [chronic recurrent multifocal osteomyelitis, CRMO] but turn out not to be. Then we can compare features across the two major groups and identify which features will be ‘for’ CMO and which features will be ‘against’ it. After this step, we’ll be able to have an expert panel incorporate their clinical experience,” Zhao said.
Diagnosis of CNO or CRMO is often delayed by 2 years or more from onset of bone pain, Zhao said, and in the absence of approved medications, children may spend many years in pain.
The researchers compared clinical, laboratory and imaging features of CNO with those of mimicking conditions. They used a REDCap online database to collect clinical and investigational features of CNO or mimicker diseases that had at least 12 months follow-up.
They collected 450 cases from 20 centers in seven countries and four continents, which were filtered by diagnosis confidence levels for CNO or its mimickers with a cut-off of +/- two (moderate confidence).
Overall, 41 cases were excluded, and the analysis included 264 CNO cases and 145 mimicker controls.
Patients with CNO were more likely female, and intermittent pain (particularly in the neck, back and upper torso) was more common than continued pain, compared with controls. However, fever was less common among patients with CNO. Compared with controls, clavicle swelling was more common in CNO, and active arthritis was less common. Sites frequently involved in patients with CNO included the thoracic spine, clavicle, sternum/manubrium, pelvic bones, bilateral femur, bilateral tibia, unilateral fibula and foot bones, with symmetric patterns of bone lesions being more common.
Imaging features, including cortical bone disruption, disorganized bone formation, mass structure, marrow infiltrate and abscess or geographic appearance, are concerning for malignancy or infection but were less common among patients with CNO. Response to antibiotics, including complete or sustained, was also less common in CNO.
“These findings are very important because they inform us of what needs to go into future criteria development,” Zhao said. “There is continuous analysis of data that we’re doing —
looking at labs in greater detail and including radiologists in our work, as well. The next step will be to conduct an expert panel using 1000minds [computer software]; we’re hoping next year we’ll be able to make it happen.”
Zhao said the researchers are still collecting cases in order to validate the criteria they develop, and he encouraged attendees to get in touch if they are interested in participating.
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Zhao Y. Abstract #1162. Presented at: ACR Convergence 2020; November 5-9, 2020 (virtual meeting).
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