E2385. The CNO Show: Imaging Features of Chronic Nonbacterial Osteomyelitis With an Emphasis on Clinico-Radiological Pearls and Pitfalls
  1. Mohammadali Saffarzadeh; University of British Columbia
  2. Syed Haydar; University of British Columbia
  3. Hugue Ouellette; University of British Columbia
  4. Paul Mallinson; University of British Columbia
  5. Gordon Andrews; University of British Columbia
  6. Peter Munk; University of British Columbia
  7. Adnan Sheikh; University of British Columbia
Chronic nonbacterial osteomyelitis (CNO) is an inflammatory disease that predominantly occurs in the pediatric population, but can affect any age group. Classically, it presents as sterile bone pain of insidious onset with associated swelling, focal tenderness, and warmth at the affected site. CNO can affect any area in the body, but the most common locations are the metaphysis of long bones in the lower extremities, pelvis, clavicle, and vertebrae. Investigating the differential diagnoses of CNO relies heavily on radiological findings at the affected site in tandem with clinical assessment of the patient. Given that CNO is often a diagnosis of exclusion, other conditions that can present with focal or multifocal mixed sclerotic and lytic lesions such as osteomyelitis, SAPHO (synovitis, acne, pustulosis, hyperostosis and osteitis) syndrome, primary and secondary bone tumors, Paget’s disease, eosinophilic granuloma, and Langerhans cell histiocytosis must be first ruled out.

Educational Goals / Teaching Points
The goal of this exhibit is to present the radiographic and Computed Tomography (CT) findings in CNO with an emphasis on utilizing radiological findings in conjunction with clinical assessment to facilitate an accurate diagnosis in the context of mixed sclerotic/lytic bone lesions. Clinical pearls and common pitfalls in diagnosis of CNO will also be highlighted. Additionally, the CT findings of conditions that can mimic CNO and present with bone pain with sclerotic lesions on imaging will be overviewed.

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques
Lytic and sclerotic bony lesions, hyperostosis, and cortical changes are among the typical radiographic and computed tomography (CT) findings of CNO. Disturbance to bone growth can also occur which will present as physeal bar on imaging in patients affected by the CNO in childhood or adolescence. Presentation of CNO at the spine will include radiological signs of kyphosis with associated vertebral body height loss. This exhibit will include a radiological assessment of CNO using two imaging modalities (x-ray and CT) at the clavicle and other common locations of disease presentation. Sclerotic and lytic lesions at various skeletal sites seen on CT in conditions that can mimic CNO will also be investigated.

Plain radiography and CT are commonly utilized for initial investigation of bone pain of insidious onset to aid in diagnosis and characterization of disease etiology. The differential diagnosis for mixed sclerotic and lytic bony lesions is wide, and radiological assessment requires clinical correlation for diagnosing patients with CNO.