Kawasaki disease with retropharyngeal edema (KD with RPE) is a rare complication, and it is diagnosed by neck CT. Most reported cases had a delayed diagnosis because those patients' conditions were misdiagnosed as retropharyngeal abscess (RPA). The purpose of this study was to differentiate KD with RPE from RPA. We performed a retrospective case-control study comparing children with KD with RPE to those with RPA hospitalized at the tertiary pediatric hospital in Tokyo between 2005 and 2011. The 39 patients revealing RPE on neck CT were divided into two groups: group A was classified as KD (n = 21) and group B was classified as non-KD (n = 18). Patients in group B were finally evaluated as having RPA clinically and were treated with antibiotic therapy. A significantly higher proportion of patients in group B complained of dysphagia (11 patients vs. 5 patients; p = 0.0170) and neck pain (17 patients vs. 12 patients; p = 0.0106). Neck CT revealed a ring enhancement (16 patients vs. no patients; p < 0.0001) and mass effect in a greater proportion of patients in group B (11 patients vs. 1 patient; p < 0.0003).
Conclusion: Careful attention to manifestations and close analyses of CT imaging may allow clinicians to differentiate KD with RPE from RPA.