Purpose or Case Report: Emphysematous osteomyelitis is a known, though rare, diagnosis which can occur in pediatric patients and can be definitively diagnosed on computed tomography (CT). To our knowledge, only 30 cases had been reported as of 2018. Our objective is to raise awareness of emphysematous osteomyelitis as an important imaging diagnosis with high morbidity and mortality. Additionally, we aim to describe the characteristic appearance utilizing CT as a gold standard, discuss underlying etiologies, and describe associated systemic findings illustrated in a case example. In pediatric patients without comorbidities, the most common causative organism of emphysematous osteomyelitis is Fusobacterium necrophorum. F. necrophorum infection commonly causes Lemierre’s syndrome, however, the two diagnoses can coexist. With the distinct CT appearance of emphysematous osteomyelitis, radiologists can alert clinicians to the diagnosis and expedite aggressive treatment.

Our patient, an 18-year-old male with a recent outpatient diagnosis of mononucleosis, presented to the emergency department (ED) for throat pain and fever. Physical examination and lab values were remarkable for posterior pharyngeal erythema and elevated serum creatinine (1.44). He was discharged with supportive management and corticosteroids. Ten days later, he returned to the ED with worsening symptoms including right hip and right ankle pain and swelling, chest pain, and dark urine output. Physical exam was significant for tachycardia, tachypnea, and right lower quadrant abdominal pain. Laboratory evaluation showed increasing serum creatinine of 2.9, leukocytosis, thrombocytopenia, and lactic acidosis. Workup showed right lung consolidation, right pleural effusion, retroperitoneal inflammation, and emphysema about the right psoas major, as well as intramedullary air within the right ilium. The patient was admitted to the pediatric intensive care unit (PICU), received broad-spectrum intravenous antibiotics, and underwent CT-guided right ilium biopsy. Bone marrow culture grew F. necrophorum, prompting additional workup including a chest CT and head and neck CTA to assess for Lemierre’s Disease. Exams demonstrated a left parapharyngeal abscess, left internal jugular vein thrombosis, multiple cavitating pulmonary septic emboli, and bilateral pleural effusions. Anticoagulation was initiated and antibiotics were narrowed to culture sensitivities. The patient improved, allowing transfer out of the PICU to the medicine floor.
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