Mixed connective tissue disease
Mixed connective tissue disease (MCTD) is an overlapping syndrome with clinical signs of SLE, systemic scleroderma (SSD), and polymyositis. The predominant sex is female (8:1).
Etiopathogenesis
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- Constantly high titers of AT to nuclear ribonucleoproteins
- Polyclonal hypergammaglobulinemia
- T-suppressor defect
- Presence of circulating immune complexes
- Deposition of IgG, IgM and complement components in the walls of blood vessels and on the basement membranes of the renal glomeruli
- Lymphocytic and plasmacytic tissue infiltration.
Pathomorphology
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- Proliferative lesion of the inner or middle lining of large and small blood vessels
- This leads to narrowing of the lumen of the vessels.
Clinical picture
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- Lupus-like manifestations
- Oligoarthritis (unlike SLE, can be erosive and lead to deformities)
- Skin lesions:
- Butterfly centrifugal erythema
- discoid elements
- alopecia
- Kidney damage:
- Proteinuria
- Hematuria
- Lack of progression of glomerulonephritis and development of renal failure (unlike SLE)
- Fever
- Lymphadenopathy
- CNS damage (rare)
- Polyserositis (not often).
- Polymyositis-like manifestations
- Proximal muscle weakness
- Myalgia
- Heliotrope edema within the eyes.
- Scleroderma-like manifestations
- Raynaud’s syndrome
- Dense swelling of the hands and sclerodactyly
- Telangiectasias, areas of hypo- and hyperpigmentation
- Esophageal injury:
- Decreased peristalsis in the distal sections
- Weakness of the esophageal-gastric sphincter
- Lung involvement (rare):
- Pleurisy
- Interstitial pneumonia
- Secondary pulmonary hypertension.
- Defeat SSS
- Pericarditis
- Myocarditis.
- Sjögren’s syndrome.
- Hashimdto’s thyroiditis.
Diagnostics
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- Laboratory research
- Anemia, leukopenia, increased ESR
- Hypergammaglobulinemia
- Antinuclear factor in high titer, mottled type of luminescence using immunofluorescence technique
- AT to extractable nuclear Ag (i.e. to ribonucleoproteins, in particular, to the protein component of U, small nuclear ribonucleoprotein) in high titer
- Anti-DNA antibodies typical of SLE are not found in MCTS
- RF (often)
- Increased concentration of muscle tissue enzymes in blood serum (CPK, less often – ACT, ALT, LDH)
- Hypocomplementemia (rare)
- X-ray examination
- X-ray of bones – erosive changes are possible, more often in small joints of the hands
- X-ray of the lungs
- Signs of an effusion
- Dissemination stimulated by interstitial changes is possible.
- Special Studies
- Echocardiography – possible signs of pericarditis
- FEGDS – assessment of the condition of the esophagus
- Measurement of the diffusion probability of the lungs by the difference in CO2 concentrations in the inhaled and exhaled air when using a mixture with a known pCO2.
Diagnostic Criteria—A definite diagnosis of CTD requires the presence of at least 4 of the following criteria:
- severe myositis
- Lung damage
- Diffusion capacity of the lungs