BCG Reactivation in a 6-Month-Old Infant: Early Diagnosis of Kawasaki Disease

Classic diagnosis of Kawasaki disease: fever lasting at least five days accompanied by erythema and cracking of the lips, strawberry tongue, and/or erythema of the oral mucosa; bilateral conjunctivitis without exudate; maculopapular rash, widespread erythroderma, or erythema multiforme-like rashes; erythema and edema of the hands and feet in the acute phase and/or periungual desquamation in the subacute phase; and the presence of at least four of the following findings: typically unilateral cervical lymphadenopathy (≥1.5 cm). However, diagnosing Kawasaki disease in infants can be challenging. In the presence of unexplained high fever, erythema developing at the Bacillus Calmette-Guérin (BCG) vaccination site should serve as a warning sign for physicians, even if typical clinical findings are not fully present. In our case, which was initially evaluated with a preliminary diagnosis of upper respiratory tract infection, Kawasaki disease was suspected based on the presence of a 3-day fever, bilateral non-purulent conjunctivitis, macular rash in the neck region, and lip erythema, along with erythema at the BCG scar. Given that the BCG vaccine is routinely administered at 2 months of age in our country, this case highlights that BCG reactivation is an important finding for the early diagnosis of infant Kawasaki disease.