Biological therapy in refractory chronic nonbacterial osteomyelitis: A case series of 19 patients.

Introduction: Chronic non-bacterial osteomyelitis (CNO) represents an autoinflammatory bone disorder. Currently there are no standardized diagnostic or treatment guidelines. The objective of the study is to describe our experience with biological therapy in children with the disease.

Methods: Retrospective chart review of patients with CNO treated with biological therapy followed at two tertiary hospitals from January 2007 to April 2020. Biologicals were started in most patients due to persistent disease activity after receiving standard therapy with at least 2 drugs (NSAIDs and corticosteroids and/or pamidronate).

Results: Twenty-five patients were diagnosed with CNO. Out of those, 19 patients (15 females) failed conventional therapy. The mean age at diagnosis was 8.8±2.9 years and the mean diagnostic delay was 6.9±8.3 months. All patients presented with bone pain and 6/19 also had fever. The most frequently affected bones were femur (9 patients), followed by clavicle, tibia and vertebrae (6, 6 and 5 patients respectively). Nine children had skin lesions. C-reactive protein was elevated in 13/19 patients (mean 20.2mg/L±11.7) and ESR in 16/19 (mean 48mm/h±29). All patients received nonsteroidal anti-inflammatory drugs, 15/19 pamidronate, 10/19 corticosteroids and 19 anti-TNF-therapy. At the last follow-up visit, 10/19 patients were still on biological therapy (8 adalimumab, 2 infliximab) and 18 out of 19 remained asymptomatic. In regards to adverse effects, one patient receiving infliximab developed S. aureus osteomyelitis and another cutaneous leishmaniosis.

Conclusions: This research emphasizes that anti-TNF-therapy represents an effective and safe alternative for patients with CNO refractory to conventional treatments.