Chronic Osteomyelitis of Long Bones: Imaging Pearls and Pitfalls in Pediatrics.

Chronic bacterial osteomyelitis is characterized by progressive inflammatory bone destruction and apposition of new bone most often caused by pyogenic bacteria. Clinical findings are nonspecific, and serum inflammatory markers can be normal. Prompt diagnosis and treatment are essential. Left untreated, chronic infection can lead to high morbidity and mortality. Imaging's major role is to suggest the correct diagnosis, exclude other diagnoses that can mimic osteomyelitis, document extent of disease, and guide interventions such as image-guided biopsy or surgical debridement. Several conditions can mimic chronic osteomyelitis clinically and radiographically. The main differential diagnoses include an oncologic process, chronic nonbacterial or chronic recurrent multifocal osteomyelitis, bone infarct in sickle cell disease, osteoid osteoma, and stress reaction/fracture. The oncologic process to consider includes metastatic neuroblastoma and Langerhans cell histiocytosis in a child younger than five years or leukemia, Ewing sarcoma, and osteosarcoma in the older age group. However, these lesions can typically be excluded based on radiographs and magnetic resonance imaging findings. Therefore, radiologist familiarity with imaging findings and mimickers is essential. In this article, we briefly review the epidemiologic, clinical, and histopathologic features of chronic bacterial osteomyelitis and emphasize imaging pearls and pitfalls, with discussion of the most common differential diagnoses.