Chronic Nonbacterial Osteomyelitis (CNO) and Takayasu Arteritis – 3 Cases in a Tertiary Pediatric Hospital and a Literature Review

Objectives Chronic nonbacterial osteomyelitis (CNO) and Takayasu arteritis (TAK) are distinct inflammatory disorders traditionally considered unrelated.[1,2] Fewer than 10 cases of co-occurrence have been reported, including 5 pediatric patients,[3] suggesting a possible overlap within the autoinflammatory spectrum. We describe 3 pediatric cases of CNO who developed TAK-like large-vessel vasculitis.

Methods We conducted a retrospective review of 3 pediatric patients diagnosed with CNO at The Hospital for Sick Children (Toronto, Canada) who later developed large-vessel vasculitis. Patients were identified through a review of the Childhood Arthritis and Rheumatic Diseases (CARD) Biobank, which was conducted under institutional Research Ethics Board (REB) approval (#1000046337).

Results Case Presentations: Case 1: A 12-year-old White-European female with CNO involving the clavicle, thoracic spine, and sacrum developed isolated pulmonary artery vasculitis at age 15, presenting with chest pain and systemic inflammation. She responded to corticosteroids and infliximab; Case 2: A 5-year-old male of Guyanese ethnicity, diagnosed with CNO involving mandible and long bones; At the age of 15 he had persistent unexplained elevated inflammatory markers; imaging revealed extensive abdominal aortic and branch vessel vasculitis as well as renal arteries, despite being asymptomatic. He required corticosteroids, infliximab, and leflunomide, with flares (new onset hypertension with imaging suggestive of SMA and renal arteries inflammation) linked to non-adherence; Case 3: An 8-year-old South Asian female with congenital anomalies (intestinal malrotation, bicornuate uterus, poly-splenia) and Failure to Thrive (FTT) at infancy was diagnosed with cervical spine CNO and developed medium/large vessel vasculitis at age 11 involving thoracic and abdominal aorta and femoral arteries, with work-up following presentation of erythema-nodosum-like lesions. She was managed with corticosteroids, infliximab and methotrexate (Table 1), (CNO and TAK - cases summary).

Conclusion This series highlights a rare but clinically relevant association between CNO and TAK-like-vasculitis. Vigilance for vascular involvement in patients with CNO is essential for timely diagnosis and management. These observations may provide clues toward understanding shared pathogenic mechanisms.

References [1.] Lim L. J Pediatr 2025;283:114636. [2.] Aeschlimann FA. Front Pediatr 2022;10:872313. [3.] Shirai T. Intern Med 2018;57:1929-1934.