To the Editor: Kawasaki disease (KD) is an acute vasculitis of unknown aetiology occurring mostly in infants and young children. KD is characterised by fever of more than 4 days’ duration; conjunctivitis; rash; cervical lymphadenopathy; erythema of the lips, oral mucosa, palms and soles; and oedema of the hands and feet.1

Coronary artery aneurysms develop in 15%–25% of untreated children,2 with attendant risk of ischaemic heart disease, myocardial infarction and sudden death.3,4 Treatment with intravenous immunoglobulin (IVIG) within the first 10 days reduces the incidence of aneurysm to less than 5%.4 A KD diagnosis is clinical, based on the recognition of a characteristic set of signs and symptoms.4 The 10%–45% of children who meet only some of the classical criteria are said to have “atypical” or “incomplete” KD. These children have a higher risk of coronary artery aneurysm than children with typical KD.4 Abdominal symptoms, including acute appendicitis and appendicular vasculitis, can occur before the development of classical features of KD.4,5 A 50% coronary artery aneurysm rate has been reported in children with KD and acute abdomen. It is still unclear whether this reflects a delay in diagnosis and treatment or is a marker of a more severe vasculitis involving the intestinal tract.

A 3-year-old boy presented with a 2-week history of remittent, high-spiking fever (37.5–39.0° C; 2–3 spikes/day), right lower quadrant abdominal pain, and McBurney’s sign with rebound tenderness. Abdominal ultrasonography suggested a diagnosis of acute appendicitis with peritonitis. The postoperative diagnosis was appendicular vasculitis with peritoneal inflammation and serous secretion.

Fever persisted despite treatment with intravenous cephalosporin. Several days later, the boy developed conjunctivitis, cracked lips, a raised erythrocyte sedimentation rate and C-reactive protein level, and thrombocytosis (715 × 109 platelets/L). KD was suspected, and an echocardiogram revealed two sacciform coronary artery aneurysms (diameters, 3.1 mm and 2.9 mm) in the proximal part of the common trunk. The child was given IVIG (2 g/kg) and oral acetylsalicylic acid (100 mg/kg per day in four divided doses). As the fever failed to resolve, the patient was given a second dose of IVIG,4 this time leading to a dramatic clinical improvement. Five days later, he developed oedema of the hands and periungual peeling of the fingers. His aspirin dose was reduced to 5 mg/kg/day. Follow-up echocardiograms at 3 months and 6 months demonstrated persistent coronary artery dilatation.

Persistent fever with conjunctivitis and cracked lips should alert clinicians to the possibility of KD. At our patient’s age, acute appendicitis is rare, and other causes of abdominal pain must be excluded. In this case, the unusual postoperative course, with persistent fever even after antibiotic treatment, was another clue to establishing the correct diagnosis.