Rheumatic fever pathophysiology
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. ; Lance Christiansen, D.O.; Associate Editor(s)-in-Chief: Cafer Zorkun, M.D., Ph.D. ; Anthony Gallo, B.S. 
Rheumatic fever is the result of an autoimmunological sequela to a virulent Streptococcus pyogenes infection in a patient who was immunologically sensitized from prior infections. During a streptococcal infection, activated antigen-presenting cells, such as macrophages, present the bacterial antigen to helper T cells. Helper T cells subsequently activate B cells and induce the production of antibodies against the cell wall of Streptococcus. However the antibodies also act against the myocardium and joints, producing the symptoms of rheumatic fever.
- Rheumatic fever is the result of an autoimmunological sequelae to a virulent Streptococcus pyogenes infection in a patient who was immunologically sensitized from prior infections, affecting periarteriolar connective tissue.
- During a streptococcal infection, activated antigen-presenting cells, such as macrophages, present the bacterial antigen to helper T cells.
- Helper T cells subsequently activate B cells and induce the production of antibodies against the cell wall of Streptococcus.
- However the antibodies may also act against the myocardium and joints, producing the symptoms of rheumatic fever.
- Contrary to the immunological protection developed during most infections, infections by Streptococcus pyogenes cause both a protective immunological and pathological autoimmunological stimulation.
- Repeated infections by Streptococcus pyogenes will cause both a heightened protective and pathological immune response
Acute rheumatic fever
- Lesions may occur in endocardium, myocardium, or pericardium.
- The inflammation may cause serofibrinous pericardial exudates described as “bread-and-butter” pericarditis, which usually resolves without sequelae.
- Involvement of the endocardium typically results in fibrinoid necrosis and verrucae formation along the lines of closure of the heart valves.
- These warty projections and irregular thickenings are known as MacCallum plaques.
Chronic rheumatic fever
- Lesions may occur in the mitral valve.
- Valve thickening may result in stenosis or regurgitation.
On gross pathology, the following are characteristic findings of rheumatic fever:
- "Fish-mouth appearance"
- Slit-like morphology; elliptical cross-sectional flow area (mitral valve) with abnormally small semi-minor axis
- Significant valvular thickening
- Thickening and shortening of the chorda tympani
Microscopic histopathological analysis
On microscopic histopathological analysis, the following are characteristic findings of rheumatic fever:
- Caterpillar cells
- Aschoff bodies found within the heart
- Jumbled, eosinophilic collagen
- Surrounded by T cells
The following are gross and microscopic images associated with rheumatic fever:
Aortic stenosis (Tricuspid aorta): gross, an example of aortic stenosis due to rheumatic fever.
Mitral scarring: gross, an example of mitral scarring due to rheumatic fever (healing phase of an infectious lesion).
Rheumatic mitral valvulitis: gross, an example of fibrosis, chorda thickening and shortening with thrombus around the large left atrium.
Rheumatic mitral valvulitis: gross, an example of acute rheumatic fever lesion along line of closure of mitral valve.
Mitral valve: gross, acute rheumatic fever.
Aschoff bodies: microscopic histopathological analysis, Aschoff bodies in rheumatic heart disease.
- ↑ Chopra P, Gulwani H (2007). "Pathology and pathogenesis of rheumatic heart disease". Indian J Pathol Microbiol. 50 (4): 685–97. PMID 18306530.
- ↑ 2.0 2.1 Rheumatic Heart Disease. Libre Pathology (2015). http://librepathology.org/wiki/index.php/Heart_valves#Rheumatic_heart_disease Accessed on October 12, 2015
- ↑ Cotran, Ramzi S.; Kumar, Vinay; Fausto, Nelson; Robbins, Stanley L.; Abbas, Abul K. (2005). Robbins and Cotran pathologic basis of disease. St. Louis, MO: Elsevier Saunders. ISBN 0-7216-0187-1.
- ↑ Pathology Education Instructional Resource. University of Alabama at Birmingham (2014). Images courtesy of Propessor Peter Anderson DVM PhD and published with permission of PEIR, Department of Pathology, University of Alabama at Birmingham. http://www.peir.net Accessed on October 12, 2015.