Q3 LONG ANSWER 10M ★ High-yield

Describe the pathogenesis, Jones criteria and morphology of rheumatic fever. Add a note on chronic rheumatic heart disease.

Pathology · 2nd Professional — Para-Clinical

Definition

Acute rheumatic fever is an immunologically mediated, multisystem inflammatory disease occurring a few weeks after a group A beta-haemolytic streptococcal pharyngitis, which may leave permanent valvular damage — chronic rheumatic heart disease.

Affects children aged 5 to 15, and remains common in India, where it is still a leading cause of acquired heart disease in the young
Follows pharyngeal infection only — never skin infection, which causes glomerulonephritis instead
Latent period of 1 to 5 weeks, by which time throat cultures are usually negative

Pathogenesis

Group A streptococcal pharyngitis in a genetically susceptible host → Antibodies form against the streptococcal M protein → molecular mimicry — the M protein resembles cardiac myosin, laminin and sarcolemmal proteins → The antibodies cross-react with host tissue — heart, joint, skin, brain → type II hypersensitivity, with CD4 T cell involvement → Inflammation of heart, joints, skin, subcutaneous tissue and basal ganglia → Healing by fibrosis in the valves → chronic rheumatic heart disease

The damage is done by the immune response, not by the organism — the streptococcus is never found in the heart
Recurrent attacks cause cumulative damage, which is the entire rationale for secondary prophylaxis

Diagnosis — the Revised Jones Criteria

Major criteria	Minor criteria
Carditis — pancarditis; the only manifestation that leaves permanent damage	Fever
Migratory polyarthritis of large joints — the commonest feature; fleeting and never deforming	Arthralgia (only if arthritis is not a major criterion)
Sydenham chorea — involuntary purposeless movements; a late manifestation, appearing months later	Raised ESR or C-reactive protein
Erythema marginatum — an evanescent, non-pruritic rash with a serpiginous margin on the trunk	Prolonged PR interval on the ECG
Subcutaneous nodules — painless, firm, over extensor surfaces and bony prominences	—

Diagnosis requires two major, or one major and two minor criteria, plus evidence of a preceding streptococcal infection — a raised or rising ASO titre, anti-DNase B, or a positive throat culture
The evidence of preceding infection is essential and is the criterion most often forgotten
Chorea and indolent carditis are exceptions and may be diagnostic alone, since they appear so late that other evidence has faded

Morphology

The Aschoff body — pathognomonic

A focus of fibrinoid necrosis surrounded by lymphocytes, plasma cells and macrophages
Anitschkow cells — plump macrophages with a central wavy ribbon of chromatin, giving the "caterpillar" appearance in longitudinal section and an "owl-eye" appearance in cross-section
Aschoff giant cells — multinucleate forms of the same cell
Found in all three layers of the heart, most reliably in the myocardium and perivascular connective tissue

Layer	Acute changes
Endocardium and valves	Small (1–2 mm), warty, firmly attached verrucae along the lines OF closure of the valve cusps; they do not embolise. MacCALLUM patches — irregular thickening of the left atrial endocardium from regurgitant jets
Myocardium	Aschoff bodies; interstitial inflammation; may cause cardiac failure and is the usual cause of death in the acute attack
Pericardium	Fibrinous or serofibrinous pericarditis — the "bread and butter" appearance; resolves without constriction

CLINICAL PEARL

Rheumatic and infective endocarditis vegetations differ in every way that matters. Rheumatic vegetations are small, firm, sterile and sit along the line of closure; they do not embolise. Infective vegetations are large, friable, teeming with organisms, and embolise readily, causing abscesses and mycotic aneurysms. Size and friability separate them at the bedside and at autopsy.

Chronic Rheumatic Heart Disease

Follows years after one or more acute attacks, from organisation and fibrosis of the valve lesions
Valve changes — leaflet thickening, commissural fusion, and shortening, thickening and fusion of the chordae tendineae
Mitral valve alone in 65–70%; mitral and aortic together in 25%; the tricuspid is occasionally involved and the pulmonary valve almost never
Mitral stenosis is the classical result, giving the "fish-mouth" or "buttonhole" orifice
Consequences — left atrial dilatation, atrial fibrillation, mural thrombus and systemic embolism, pulmonary hypertension, right heart failure, and a greatly increased risk of infective endocarditis

Investigations and Course

Investigation	Finding
ASO titre and anti-DNase B	Raised or rising — evidence of preceding streptococcal infection
Throat culture	Often negative by the time of presentation, because of the latent period
ESR and C-reactive protein	Raised — minor criteria; useful for monitoring activity
ECG	Prolonged PR interval; other conduction disturbance
Echocardiography	Valvulitis and regurgitation, including subclinical carditis; now part of the revised criteria in high-incidence settings
Chest radiograph	Cardiomegaly; pulmonary congestion

The acute attack lasts about 3 months and is self-limiting; the arthritis and fever settle completely
Carditis is the only manifestation that leaves permanent damage, and its severity in the first attack predicts the later valve disease
Recurrences are commonest in the first 5 years and each adds further valve injury

Applied Aspects

Primary prevention — prompt treatment of streptococcal sore throat with penicillin prevents the first attack; this is cheap and effective and remains badly underused in India
Secondary prophylaxis is the cornerstone — benzathine penicillin every 3 to 4 weeks, continued for years (to age 21, or longer with carditis or valve disease). Recurrences cause cumulative damage
"Rheumatic fever licks the joints but bites the heart" — the arthritis is dramatic and transient, the carditis quiet and permanent
Echocardiography detects subclinical carditis and is now part of the revised Jones criteria in high-incidence populations such as India
Antibiotic prophylaxis before dental and surgical procedures in those with established valve disease, to prevent infective endocarditis
Mitral stenosis in pregnancy is dangerous, since the increased cardiac output and tachycardia across a fixed orifice precipitate pulmonary oedema
Balloon mitral valvotomy is effective and relatively cheap for suitable pliable valves, and is widely used in India
Adherence to monthly injections is the practical problem, and organised registers with recall improve it substantially

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