This patient's presentation is consistent with a diagnosis of acute rheumatic fever and associated carditis. Histologic findings associated with this condition include Aschoff bodies, interstitial myocardial granulomas composed of surrounding Anitschkow or caterpillar cells, which are plump macrophages with abundant cytoplasm and central, ovoid nuclei with slender ribbons of chromatin.
Rheumatic fever develops several weeks following Group A strep pharyngitis and is most common in children between the ages of 5 to 15. Rheumatic carditis can take the form of endocarditis, myocarditis, or pericarditis. Rheumatic endocarditis is characterized by mitral valve prolapse early in the course and mitral stenosis later in the disease, with deposition of sterile valvular vegetations. Myocarditis containing Aschoff bodies, fibrinoid necrosis surrounded by reactive histiocytes, is pathognomonic for the diagnosis of acute rheumatic heart disease. Finally, rheumatic pericarditis manifests as a friction rub with the characteristic symptom of precordial chest pain, relieved with sitting/leaning forward.
Hahn et al. discuss the diagnosis and management of poststreptococcal illnesses. Manifestations of rheumatic fever include carditis, skin disease, polyarticular arthritis, chorea, and acquired valvular disease. Evaluation begins with pursuing signs of inflammation, including CBC, ESR, and CRP as well as evidence of preceeding streptococcal infection, starting with antistreptolysin O (ASO) titers.
Cilliers et al. review the utility of anti-inflammatory therapy for the treatment of carditis in acute rheumatic fever. They conclude that there is little evidence showing benefit of corticosteroids or IV immunoglobulins in reducing the risk of heart valve lesions in patients with acute rheumatic fever. The development of new anti-inflammatory agents as well as improved echocardiograhic techniques allowing for more objective assessment of cardiac outcomes both point towards the need for additional future investigation.
Illustration A depicts an Aschoff body seen in rheumatic heart disease.
Illustration B highlights Anitschkow cells, note the wavy "caterpillar" chromatin.
Illustration C summarizes the pathogenesis of rheumatic heart disease.
Answer 1: Atypical lymphocytosis in the setting of a positive heterophil antibody test is consistent with a diagnosis of infectious mononucleosis caused by EBV.
Answer 2: This finding is consistent with a diagnosis of malaria.
Answer 3: The deposition of monosodium urate crystals in synovial fluid describes the histological findings associated with gout.
Answer 5: These findings are consistent with a diagnosis of systemic lupus erythematous (SLE).
Hahn RG, Knox LM, Forman TA. Evaluation of poststreptococcal illness. Am Fam Physician. 2005 May 15;71(10):1949-54.
PMID:15926411 (Link to Abstract)
Cilliers A, Manyemba J, Adler AJ, Saloojee H. Anti-inflammatory treatment for carditis in acute rheumatic fever. Cochrane Database Syst Rev. 2012 Jun 13;6:CD003176.
PMID:22696333 (Link to Abstract)
USMLE World Step 1 QBank Question #240. Copyright © USMLEWorld, LLC 2012