A case of Kawasaki disease mimicking acute appendicitis

Kawasaki disease (KD) is an acute vasculitis of unknown aetiology occurring mostly in infants and young children. KD is characterized by fever (≥5 days), conjunctivitis, rash, cervical lymphadenopathy, lips, oral mucosa, palms and soles erythema, hands and feet oedema [1]. Coronary artery aneurysms develop in 15-25% of untreated children [2] with risk of ischemic heart disease, myocardial infarction, sudden death [3;4]. Treatment with intravenous gamma globulins (IVIG) within the first 10 days reduces the incidence of aneurysms to <5% [4]. The KD diagnosis is clinical, based on the recognition of a characteristic set of signs and symptoms [4]. Children not meeting traditional criteria are considered as “atypical” or “incomplete” KD (10-45%) possessing higher risk of coronary artery aneurysms [4]. Abdominal symptoms, including acute appendicitis and appendicular vasculitis, can occur before the development of classical features [4;5]. A 50% coronary artery aneurysm rate is reported in KD children with a surgical abdomen. It is still unclear if it reflects the delay in diagnosis and treatment or it is a marker of a more severe vasculitis, involving intestinal tract. Our clinical case is a 3 years-old child with fever (remittent, high-spiking 37.5÷39 °C, 2-3 spikes/day, persisting for two weeks), right lower quadrant abdominal pain, McBurney’s sign, rebound tenderness. Abdominal echography confirmed acute appendicitis with peritonitis diagnosis. Appendicular vasculitis with peritoneal inflammation and serous secretion was postoperative diagnosis. After intervention and cephalosporin injection fever persisted; some days later, he presented conjunctivitis, lips cracking, elevation of the erythrocyte sedimentation rate and C-reactive protein, thrombocytosis (715.000); KD was suspected and echocardiogram revealed two sacciform coronary artery aneurysms in the common trunk proximal part (diameter: 3.1, 2.9 mm). He received IVIG (2 g/kg) and acetylsalicylic acid (100 mg/kg/day in four doses). He failed to defervesce and received a second IVIG dose [4], with a dramatic clinical improvement. Five days later he developed hands oedema and periungueal fingers peeling; he was kept on Aspirin at 5 mg/kg/day. On follow-up echocardiograms demonstrated persistent coronary artery dilatation. Persistent fever with conjunctivitis and lips cracking is very important marker for KD suspicion. At our patient’s age acute appendicitis is rare; on the contrary medical aetiology of abdominal pain must be excluded. The unusual post-operative course with persistent fever, also after antibiotics administration, is another marker for correct diagnosis. We suggest to extend differential diagnosis of abdominal pain and fever also to KD and to evaluate by echocardiogram all suspected KD.