What is Rheumatic Fever?
Rheumatic fever is an inflammatory disease that can develop as a complication of inadequately treated strep throat or scarlet fever. These conditions are caused by infection with group A Streptococcus bacteria. Rheumatic fever primarily affects the heart, joints, skin, and brain. In the context of histology, it is important to understand the cellular and tissue-level changes that occur during this disease.
Histopathological Features
In rheumatic fever, several histopathological features are key indicators of the disease. One of the hallmark features is the presence of Aschoff bodies, which are areas of fibrinoid necrosis surrounded by lymphocytes, plasma cells, and macrophages. These nodules are particularly found in the myocardium and are a vital histological sign of rheumatic heart disease. Cardiac Involvement
Rheumatic fever can lead to rheumatic heart disease, which involves the inflammation of the heart valves. Histologically, this manifests as thickening and fusion of the valve leaflets, along with neovascularization and fibrosis. The mitral valve is most commonly affected, followed by the aortic valve. The presence of Aschoff bodies in the myocardium is also a significant finding.Joint Involvement
Although the primary focus in histology often lies on cardiac tissues, rheumatic fever also involves the joints, leading to a condition known as migratory polyarthritis. Histologically, affected joints show synovial hypertrophy, increased vascular permeability, and infiltration by inflammatory cells such as neutrophils and lymphocytes. Skin and Brain Involvement
In the skin, histological examination might reveal subcutaneous nodules composed of fibrinoid material and surrounded by chronic inflammatory cells. Another skin manifestation is erythema marginatum, which shows perivascular inflammation. In the brain, Sydenham chorea, a neurological manifestation, is characterized by basal ganglia inflammation, though this is more difficult to observe histologically.Diagnosis and Histological Techniques
Histological diagnosis of rheumatic fever often involves biopsy of affected tissues, particularly the heart. Standard staining techniques like Hematoxylin and Eosin (H&E) are used to identify Aschoff bodies and inflammatory infiltrates. Immunohistochemistry may also be employed to detect specific markers of inflammation and cellular damage. Why is Histology Important in Rheumatic Fever?
Histology plays a crucial role in diagnosing and understanding the progression of rheumatic fever. By examining tissues at the microscopic level, pathologists can identify characteristic features that confirm the diagnosis and help differentiate it from other inflammatory diseases. This is essential for guiding appropriate treatment and managing complications.
Treatment and Prognosis
While histology is invaluable for diagnosis, treatment primarily involves antibiotics to eradicate the streptococcal infection and anti-inflammatory medications to reduce tissue damage. The histological findings can provide insights into the severity of the disease and help predict long-term outcomes, particularly in assessing the extent of cardiac damage.Conclusion
Rheumatic fever is a complex disease with significant histological features that aid in its diagnosis and management. Understanding the histopathological changes in the heart, joints, skin, and brain is essential for healthcare professionals. By linking these microscopic changes to clinical manifestations, histology provides a comprehensive understanding of this multifaceted disease.
