Review Question - QID 213427

A 13-year-old girl is brought to the clinic by her parents for joint pain for the past 4 days. She reports a 6/10, intermittent, dull pain in her knees and ankles. The pain does not stay in one place and over the past day, her right knee has become red and swollen. She endorses subjective fever and fatigue but denies chest pain, dizziness, abdominal pain, gastrointestinal signs, or urinary changes. Her past medical history is unremarkable except for an episode of sore throat 3 weeks ago. A physical examination demonstrates an erythematous, swollen right knee that is tender upon palpation and skin findings on the upper left arm shown in Figure A. What finding would you expect in this patient?