A Case of Incomplete and Atypical Kawasaki Disease Presenting with Retropharyngeal Involvement.

Background: Kawasaki disease (KD) is a childhood acute febrile vasculitis of unknown aetiology. The diagnosis is based on clinical criteria, including unilateral cervical lymphadenopathy, which is the only presenting symptom associated with fever in 12% of cases. A prompt differential diagnosis distinguishing KD from infective lymphadenitis is therefore necessary to avoid incorrect and delayed diagnosis and the risk of cardiovascular sequelae. Case presentation: We describe the case of a 4 years old boy presenting with febrile right cervical lymphadenopathy, in which the unresponsiveness to broad-spectrum antibiotics, the following onset of other characteristic clinical features and the evidence on the magnetic resonance imaging (MRI) of retropharyngeal inflammation led to the diagnosis of incomplete and atypical KD. On day 8 of hospitalisation (i.e., 13 days after the onset of symptoms), one dose of intravenous immunoglobulins (IVIG; 2 g/kg) was administered with rapid defervescence, and acetylsalicylic acid (4 mg/kg/day) was started and continued at home for a total of 8 weeks. Laboratory examinations revealed a reduction in the white blood cell count and the levels of inflammatory markers, thrombocytosis, and persistently negative echocardiography. Clinically, we observed a gradual reduction of the right-side neck swelling. Fifteen days after discharge, the MRI of the neck showed a regression of the laterocervical lymphadenopathy and a resolution of the infiltration of the parapharyngeal and retropharyngeal spaces. Conclusion: Head and neck manifestations can be early presentations of KD, which is frequently misdiagnosed as suppurative lymphadenitis or retropharyngeal infection. A growing awareness of the several possible presentations of KD is therefore necessary. Computed tomography (CT) or MRI can be utilised to facilitate the diagnosis.