Following a severe sore throat, a 15-year-old boy feels unwell. He has had pain and swelling in his elbows and knees, and cardiac examination reveals new mitral regurgitation and tachycardia. Which of the following might also be seen on further examination?

Major manifestations of rheumatic fever include carditis, migratory polyarthritis, chorea, erythema marginatum, and subcutaneous nodules. Minor manifestations include arthralgia, fever, elevated acute phase reactants (ESR, C-reactive protein), and prolonged PR interval. The diagnosis is made with two major or one major and two minor criteria, and evidence of group A streptococcal infection (positive throat culture or rapid streptococcal antigen test, or rising antibody titers).