A 20-year-old woman presents to the clinic with fever and arthritis. She reports that she developed these symptoms over the past few days, and the pain seems to be jumping from one joint to the next. There is no significant medical or family history, and she does not smoke or use illicit drugs. She reports that she had a throat infection 3 weeks ago, but she denies any recent exposure to sick contacts or recent sexual activity. The patient has a temperature of 38.6°C, blood pressure of 124/78 mmHg, heart rate of 88 beats per minute, respiratory rate of 16 breaths per minute, and oxygen saturation of 100% on room air. On examination, she has a 2/6 blowing systolic murmur at the apex. There is erythema and swelling of her knees as well as her left elbow and wrist, and there are no skin or nail findings. Her white blood cell count is 15,000/mm3 and the erythrocyte sedimentation rate is 45 mm/h. Antistreptolysin O titers are positive; blood cultures are drawn and are negative.
Which of the following is the most likely diagnosis?
A. Rheumatoid arthritisRheumatic fever. One complication of untreated group A Streptococcal infection is rheumatic fever, which is an autoimmune disease that usually occurs 2 to 4 weeks after pharyngitis. It is usually seen in adolescents and is rare in adults. Diagnosis is made using the modified Jones criteria: evidence of strep infection plus two major criteria or one major criterion and two minor criteria. Major criteria include migratory polyarthritis, carditis, erythema marginatum (ring-like macular rash), Sydenham chorea, and subcutaneous nodules. Minor criteria include fever, arthralgia (painful joints without swelling), leukocytosis, elevated ESR or CRP, AV block on ECG, and previous rheumatic heart disease. This patient has two major criteria (polyarthritis and carditis) and three minor criteria (fever, leukocytosis, and elevated ESR), making the diagnosis of rheumatic fever likely. The murmur of mitral regurgitation in this patient is likely a result of valvulitis (meeting the criterion of carditis), since rheumatic fever can cause inflammation of any heart structure from the pericardium to the endocardium. Patients should be treated with antibiotics (penicillin) and aspirin if carditis is present.
(A) Rheumatoid arthritis may present with fever and symmetric polyarthritis; however, the temporal relation to pharyngitis should make the reader suspect rheumatic fever instead. (B) Gonococcal arthritis is a good diagnosis to consider in young sexually active patients presenting with fever, polyarthritis, and skin lesions (usually pustules). When this diagnosis is considered, cultures should be drawn from multiple sites (cervix, anus, synovium, etc.) to increase the diagnostic sensitivity; however, this patient is not sexually active and does not have any skin findings. (D) Infective endocarditis is diagnosed using the modified Duke criteria, which she does not meet. She has a new regurgitant murmur on examination; however, this can also occur in rheumatic fever from valvulitis.