Letters to the Editor

20 December 2007 Dear Editor, BCG SITE INFLAMMATION: A USEFUL DIAGNOSTIC SIGN IN INCOMPLETE KAWASAKI DISEASE Kawasaki disease (KD) is an acute, systemic vasculitis of unknown aetiology that occurs predominantly in infants and young children. Coronary artery involvement with aneurysms or ectasia occurs in 15–25% of untreated cases, with sudden death from myocardial infarction in 1%.1 Although diagnostic criteria for KD, endorsed by the American Heart Association, are widely used in Australasia, incomplete cases in young infants with coronary abnormalities have been reported.2, 3 We report a case of incomplete KD in which reactivation and inflammation of a previous Bacille Calmette-Guerin (BCG) immunisation site was a clue to the correct diagnosis. A previously well 11-month-old girl was treated for right otitis media by her General Practitioner. Immunisations were up to date, including BCG at birth. Despite successive courses of amoxicillin and cotrimoxazole, she remained febrile. On day 11 of her illness, she was noted to be febrile, 38°C, and very irritable. There was mild pharyngitis, a non-pruritic macular erythematous rash on her trunk, and redness of her palms and soles. She was referred to a hospital. Upon examination, she was afebrile but miserable. In addition to the findings mentioned earlier, we noted redness of her upper eyelids but no conjunctivitis or other mucosal changes. There were multiple small (<0.5 cm) lymph nodes in her neck, no hepatosplenomegaly and no arthritis. The admitting doctor documented ‘a large BCG scar, left upper arm, inflamed’. Laboratory investigations revealed normal haemoglobin concentration of 124 g/L (110–140), normal white cell count of 8.9 × 109/L (5–12), normal differential count and an elevated platelet count of 644 × 109/L (150–400). C-reactive protein was <3 mg/L (<5). A tentative diagnosis of Viral infection NOS was made and she was discharged on symptomatic treatment. At follow-up on day 18 of her illness, she remained afebrile and irritable. The rash had resolved. Fine scaling desquamation of fingers, toes and BCG scar was seen. Further investigation revealed a raised serum gamma glutamyl transpetidase (GGT) of 67 U/L (15–30), normal platelet count of 373 × 109/L (150–400), CRP of <3 mg/L (<5) and ESR of 7 mm/h (1–10). Sterile pyuria (100–500 leukocytes/high power field) was found on urinalysis. Streptococcal serology was negative. A paediatrician reviewing her case and aware of the possible significance of BCG scar changes, diagnosed probable incomplete KD. Echocardiogram confirmed aneurysmal dilatation of the proximal left main coronary artery with an internal diameter of 3 mm (Z-score + 2.5) consistent with KD. In view of her clinical improvement and normal inflammatory markers, she was treated with low dose aspirin only. Intravenous gamma globulin was not given. Repeat echocardiogram at 6 weeks was normal. To our knowledge, this is the first published Australasian case of KD, diagnosed after BCG site changes. Other recent case reports from India,4 Canada5 and the United Kingdom6 have highlighted the specificity of BCG site reactivation and inflammation as a sign of KD. The reason for the reaction is unclear but studies suggest molecular mimicry between specific epitopes of mycobacterial and human Heat Shock Protein 65.7 BCG site changes are not included in the classic clinical criteria for KD published by the American Heart Association. However, they are mentioned among ‘other clinical findings’ that may be present in some cases.1 Awareness of this sign among Australasian paediatricians is likely to be low as BCG vaccination is only recommended for high-risk populations. An earlier report from Japan, where KD and BCG vaccination are both more common than in Australasia, found that 121 (43%) of 281 children who had KD had cutaneous reactions at their BCG site.8 Others have suggested that awareness of this sign may lead to earlier diagnosis and treatment of incomplete cases.7 Based on this case and previous reports, we advise paediatricians to examine patients with suspected KD for evidence of previous BCG immunisation, and to treat evidence of reactivation, inflammation or induration as highly suspicious.

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