A 12-year-old boy is brought to emergency following a tonic-clonic seizure. He has a 2-month history of behavioral disturbances and a 1-week history of fever and swelling of the left knee. His hemoglobin is 9.5 g/dL, WBC 3500/μL, and platelets 50,000/μL. A Coombs test is positive. Urinalysis shows blood and protein. Which of the following is the most likely explanation for these findings?
Hodgkin disease
Henoch-Schönlein purpura
Mononucleosis
Systemic lupus erythematosus
Viral encephalitis
