Diagnosis, treatment and monitoring of chronic nonbacterial osteomyelitis (CNO) and chronic recurrent multifocal osteomyelitis (CRMO) - Evidence, practice and consensus-based recommendations from the German pediatric rheumatology society (GKJR).

BACKGROUND: Chronic nonbacterial osteomyelitis (CNO), sometimes also referred to as chronic recurrent multifocal osteomyelitis (CRMO), is a rare autoinflammatory bone disease primarily affecting children and adolescents. In the absence of diagnostic criteria and biomarkers, CNO remains a diagnosis of exclusion, and treatment is largely empiric.

OBJECTIVE: This initiative of the German Society of Pediatric and Adolescent Rheumatology (GKJR) aimed to develop evidence-, practice-, and consensus-based recommendations for the diagnosis and management of CNO, incorporating current knowledge on pathophysiology, therapeutic strategies and disease monitoring.

METHODS: Based on a systematic literature review and a subsequent Delphi survey, preliminary statements were developed. This was followed by expert group voting exercises (nominal group exercise) to agree final statements and recommendations.

RESULTS: Statements and recommendations were developed for the diagnosis, treatment and disease monitoring of CNO in a multidisciplinary expert group, involving patients/families. Where available, diagnostic workup should include whole-body skeletal imaging (usually MRI). Treatment options include first-line (NSAIDs, short-term corticosteroids) and second-line (conventional and/or biologic DMARDs, bisphosphonates) agents. In patients with vertebral involvement, rapid treatment with bisphosphonates and/or TNF inhibitors is recommended. As CNO is a chronic disease, long-term monitoring is recommended, including follow-up after treatment discontinuation.

CONCLUSION: Although evidence levels are low to moderate, consensus statements and recommendations provide structured guidance for clinicians diagnosing and treating CNO. They provide a framework for harmonized care aiming at improved long-term outcomes.