Mixed connective tissue disease
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor: Cafer Zorkun, M.D., Ph.D. [2]
Synonyms and keywords: MCTD; Mixed connective tissue disorder; Sharp's syndrome
Overview
Mixed connective tissue disease (MCTD) or Sharp's syndrome is a human autoimmune disease in which the immune system attacks the body. MCTD combines features of polymyositis, systemic lupus erythematosus, and systemic scleroderma and is thus considered an overlap syndrome. MCTD commonly causes joint pain/swelling, Raynaud phenomenon, muscle inflammation, and scarring of the skin of the hand. It does not typically cause kidney disease or seizures. Distinguishing laboratory characteristics are a positive, speckled anti-nuclear antibody and an anti-U1-RNP antibody.[1]
Pathophysiology
There are no specific histologic findings that aid in the diagnosis of Mixed Connective Tissue Disorder as a separate autoimmune disease. For example, nephritis in MCTD is usually indistinguishable from lupus nephritis.
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Fibrous Pericarditis in MCTD
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Cellular aggregates in perivascular space and adjacent myocardium
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Cross Section of Intramural Coronary Artery
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Small pulmonary artery in patient with MCTD and pulmnonary hypertension
Diagnosis
- Raynaud’s phenomenon
- Swollen fingers or hands
Anti–U1 small nuclear RNP positive
Mixed Connective Tissue Disorder Findings
A.Systemic lupus erythematosus–like findings
- Polyarthritis
- Lymphadenopathy
- Facial erythema
- Pericarditis or pleuritis
- Leukopenia (<4,000/mm3) or thrombocytopenia (<100,000/mm3)
B.Progressive Systemic Sclerosis –like findings
- Sclerodactyly
- Pulmonary fibrosis, restrictive changes of the lung (forced vital capacity <80% of predicted), or reduced carbon monoxide diffusing capacity (<70% of predicted)
- Hypomotility or dilatation of esophagus
C.Polymyositis-like findings
- Muscle weakness
- Elevated serum level of muscle enzymes (creatine kinase)
- Myogenic pattern on electromyogram
MCTD is characterized by anti–U1 small nuclear RNP positivity.
Cardiac Involvement in MCTD
Cardiovascular abnormalities associated with mixed connective tissue disease are rare. Presence of any of the complications listed below indicates unfavorable prognosis;
- Acute pericarditis and/or pericardial effusion,
- Mitral valve prolapse,
- Intimal hyperplasia of coronary arteries,
- Perivascular and myocardial leukocytic infiltrates,
- Pulmonary hypertension.
- Coronary Artery Disease (although it is rarer, ACS may occur secondary to vascular changes and underlying CAD. The youngest patient with MCTD and ACS in literature was 18 years old)[2]
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A teenager with MCTD presented as ACS before PCI
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A teenager with MCTD presented as ACS post PCI
References
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