A 9 year old boy presented to the casualty with high fever, pruritic erythematous rash, joint pain and lymph node enlargement. There is a history of upper respiratory tract infection for which he was on cefaclor - 7 days completed of a 10 day course. The most likely diagnosis is?: (A) Serum sickness like illness, (B) Hemolytic-uremic syndrome, (C) Kawasaki disease, (D) Type III hypersensitivity
Answer is A. Serum sickness like reaction can occur following the use of ceain drugs, especially cefaclor in children. It presents with an uicarial / purpuric rash, ahritis, lymphadenopathy and fever. But unlike true serum sickness (type III hypersensitivity response), it is not caused by circulating immune complexes.