A 10-year-old boy is brought to the pediatrician by his mother due to a 3-day history of fever, fatigue, and joint pains. He had a sore throat approximately 3 weeks ago that resolved without medical attention. The mother reports that over the past day, he has complained of pain that started in his right knee and then shifted to his left ankle. She also noticed he seems unusually clumsy and has had difficulty writing compared with his usual neat handwriting. He has no significant past medical history and takes no medications. Immunizations are up to date. Family history is unremarkable. Vital signs are temperature 38.7°C (101.7°F), blood pressure 106/68 mmHg, pulse 102 beats/min, and respirations 18/min. Cardiac examination reveals a new grade II/VI holosystolic murmur at the apex. His joints are tender but not swollen. Skin examination shows erythematous, serpiginous, non-pruritic lesions on the trunk.
Neurologic examination reveals mild choreiform movements of the hands. Which of the following is the most likely diagnosis?
C) Rheumatic fever
Rheumatic fever is a post-streptococcal autoimmune complication that typically occurs 2–4 weeks after untreated or inadequately treated pharyngitis caused by group A Streptococcus (Streptococcus pyogenes). The diagnosis is made using evidence of prior strep infection, and two major criteria or one major and two minor Jones criteria.
Major Criteria - JONES Mnemonic
- Joints: arthritis (usually migratory polyarthritis involing the large joints)
- Obvious carditis and valvulitis (pericarditis, myocarditis, or endocarditis)
- Nodules (subcutaneous)
- Erthema marginatum rash
- Sydenham chorea (neurological disorder causing rapid, jerking movements)
Minor Criteria
- Fever
- Arthralgia (joint pain)
- Elevated erythrocyte sedimentation rate or C-reactive protein
- Prolonged PR interval on electrocardiogram
This patient meets the major criteria as follows: migratory arthritis (joint pain that began in the right knee and shifted to the left ankle), carditis (a new holosystolic murmur, likely indicating mitral regurgitation), Sydenham chorea (neurologic findings such as clumsiness and difficulty with fine motor tasks), and erythema marginatum (presence of serpiginous, non-pruritic rash on the trunk). He also meets minor criteria, including fever and arthralgia The history of recent sore throat provides presumptive evidence of recent streptococcal pharyngitis, satisfying the requirement for evidence of prior infection. Thus, this child meets multiple major criteria and minor criteria in the context of a recent streptococcal infection, confirming a diagnosis of rheumatic fever.
Answer choice A: Infective endocarditis, is incorrect. Infective endocarditis involves continuous bacteremia, often with fever, a murmur, and possibly embolic or immune-related signs. However, it usually occurs in individuals with underlying valvular disease or intravenous drug use, and it is not preceded by pharyngitis. Chorea and erythema marginatum are not features of infective endocarditis.
Answer choice B: Juvenile idiopathic arthritis, is incorrect. Juvenile idiopathic arthritis presents with persistent arthritis lasting ≥6 weeks in a child under age 16. It may include systemic symptoms (in some subtypes), but it typically does not include carditis, chorea, or erythema marginatum, nor is it associated with a preceding streptococcal infection.
Answer choice D: Scarlet fever, is incorrect. Scarlet fever is an acute illness caused by streptococcal exotoxins, presenting with fever, pharyngitis, and a sandpaper-like rash. It occurs concurrently with streptococcal pharyngitis and does not cause migratory arthritis or chorea. It also lacks cardiac and neurologic findings.
Answer choice E: Systemic lupus erythematosus, is incorrect. Systemic lupus erythematosus (SLE) may present with fever, arthritis, rash, and sometimes carditis, but it is rare in young children and does not follow streptococcal infection. The presence of chorea, erythema marginatum, and a new murmur in the context of recent pharyngitis supports rheumatic fever rather than SLE.
Key Learning Point
Rheumatic fever is a type II hypersensitivity reaction that occurs after infection with Streptococcus pyogenes and is diagnosed using the Jones criteria. It classically presents with migratory polyarthritis, carditis, chorea, erythema marginatum, and subcutaneous nodules, especially in school-aged children.
