More than 50% of KD patients have atypical presentations that may result in delayed or missed diagnosis and, consequently, high rates of vascular damage. We present in this paper case of KD that presented with a retropharyngeal abscess-like lesion, which is a rare presentation.

Previous literature has shown that 90% of KD patients present with variable head and neck manifestations such as facial exanthema, conjunctivitis, oral mucosal changes, and pharyngitis. Less common presentations are otitis media, torticollis, deep neck infection-like symptoms, meningismus, and acute tonsillitis have been described [7].

Lymphadenopathy as a KD criterion is the least common diagnostic feature (50–75%), as the incidence of the other criteria occurs in 80–90% of the cases. Lymphadenopathy is described as the initial presenting symptom in 12%. Deep neck infection-like presentation is described in only less than 5% of all the patients with head and neck manifestations [2, 9, 13]. Signs and symptoms of retropharyngeal involvement, such as stridor, neck pain, and dysphagia, are less common in KD than in retropharyngeal abscesses [7].

Peritonsillar, retropharyngeal and parapharyngeal swelling are uncommonly reported as initial manifestations of KD. The precise pathophysiology of the association of KD with retroparapharyngeal pathology is unclear, with inflammation and edema hypothesized as the main mechanisms [3, 8].

Tashiro et al. described the typical ultrasound appearance of lymphadenopathy in KD patients as multiple hypoechoic–enlarged nodes forming a palpable mass resembling a cluster of grapes. This is in comparison to the appearance of bacterial lymphadenitis, described as a well-defined mass with a large central hypoechoic area surrounded by satellite normal-sized lymph nodes [18].

Pontell et al. reported the first case of KD mimicking a retropharyngeal abscess in 1994 [9, 10]. Glasier et al. reported that there might be an overlapping CT density number between cellulitis, adenopathy, and abscess, which may lead to false interpretations [19].

Poor response to antibiotic therapy and a negative aspirate culture may be additional diagnostic clues to correctly diagnosing KD [2].

Uveitis can be part of KD during the first week of illness; about three-fourths of children are photophobic, a consequence of anterior uveitis, 64 which peaks between 5 and 8 days of illness and is more common in children over 2 years old [20].

Our literature review found sixteen similar reported cases in the last thirty years. We summarized the clinical presentation, imaging findings, surgical and echocardiographic findings, and antibiotics treatment in Table 1.

The KD patients with abscess-like lesions were predominantly males (82%), with an age range from 10 months to 9 years, with a mean age of 5 years, which is considered higher than the average age of patients with KD. The majority of the cases (94%) initially presented with fever and neck swelling, without additional clinical criteria, leukocytosis. Leukocytosis was in all patients with an average of 18,500 WBC/μL. All the cases were initially considered for possible deep-neck bacterial infection, prompting antibiotic therapy and imaging studies. CT\MRI imaging was performed in all the cases, with findings suspicious for retropharyngeal disease, but in the majority, without enhancement. Indeed, low-density cervical lesions demonstrating minimal to no enhancement should raise the possibility of KD.

Intravenous antibiotics were administered in 16 patients (94%), and surgical drainage was attempted in 7 patients (41%), with two 2 cases (11%) of purulent fluid, only one of them being culture positive for Staphylococcus aureus.

As with our patient, the diagnosis of KD was made in these cases when the fever persisted and other characteristic features developed. The diagnosis was delayed beyond nine febrile days in 5 patients (30%). All the patients had a dramatic and fast clinical improvement with resolution of fever within 48 h after IVIG administration; the majority even showed improvement in the first 24 h. Most of the patients responded to one dose of IVIG; in only two cases, two doses of IVIG were administered due to slow response, and in these two cases, the diagnosis was not delayed and, they were diagnosed on the 7th day of fever.

41% of the patients had cardiac manifestations compared to less than 20% in the general pediatrics pediatric population who are diagnosed with Kawasaki disease.

In summary, we present our patient and review 17 cases reported over 30 years (since 1990), presenting with clinical presentation and radiological findings consistent with the presence of a retropharyngeal abscess. Nearly all patients were treated with antibiotics and surgical exploration without improvement. All the cases responded promptly to IVIG therapy. Cardiac involvement was more common than expected in other cases of KD.