A 6-year-old boy developed high fever, urticarial plaques, and painful knee and ankle swelling 10 days after a course of cefaclor. Complement levels are normal and there is no proteinuria. Symptoms settled with antihistamines and NSAIDs without corticosteroids. Which statement correctly distinguishes his condition from classic serum sickness?
- A It lacks immune complex deposition, hypocomplementaemia, vasculitis and renal involvement ✓
- B It involves circulating immune complexes and hypocomplementaemia
- C It is caused by IgE-mediated mast cell degranulation
- D It characteristically progresses to membranous glomerulonephritis
Correct answer: A. It lacks immune complex deposition, hypocomplementaemia, vasculitis and renal involvement
Explanation
Serum sickness-like reaction, classically linked to cefaclor in children, mimics true serum sickness with fever, urticaria and arthralgia but differs immunologically: there are no circulating immune complexes, no hypocomplementaemia, no vasculitis and no renal involvement, and it settles with symptomatic treatment. True serum sickness from heterologous proteins features immune complex deposition with low complement. IgE mediation defines ordinary urticaria, not this entity.
Reference: Nelson Textbook of Pediatrics, 21st ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.