A 14-year-old boy is brought to the emergency department by his parents for joint pain following the acute onset of a diffuse, pruritic rash for the past 24 hours. A week ago, he was diagnosed with pharyngitis after returning home from summer camp and is currently taking antibiotics. There is no family history of serious illness. His temperature is 38.5°C (101.3°F), pulse is 90/min, and blood pressure is 110/70 mm Hg. Physical examination shows periorbital edema, generalized lymphadenopathy, and well-circumscribed, erythematous, confluent skin lesions of variable sizes up to several centimeters in width over his entire body. There is pain on passive movement of wrists and ankle joints bilaterally. Urine dipstick shows 1+ proteinuria. There is no hematuria. Which of the following findings is most likely to accompany this patient's condition?

Question

Quizplus · Accepted Answer

Eductional Objective: Serum sickness is a type III hypersensitivity reaction to nonhuman proteins characterized by vasculitis resulting from tissue deposition of circulating immune complexes.  Clinical findings include fever, pruritic skin rash, arthralgias, and low serum C3 and C4 complement levels.

A 14-Year-Old Boy Is Brought to the Emergency Department by His