What Is Mixed Connective Tissue Disease?

In 1972, Sharp et al. First proposed a mixed manifestation of systemic lupus erythematosus (SLE), polymyositis (PM), scleroderma (SSc), rheumatoid arthritis (RA) and other diseases at the same time or at different times. The disease with high titer titer type ANA and high titer U ₁ RNP antibody is named mixed connective tissue disease (MCTD). For many years, although MCTD is an early manifestation of one of the above diseases or a subtype of the disease, or it is an independent disease, there is still controversy, but most scholars still accept this nomenclature. There is indeed a group of disorders manifesting this characteristic in the antibody assay. Mixed connective tissue disease (MCTD) is mainly manifested as Raynaud's phenomenon, finger swelling, rash, joint and lung damage, and high titer antinuclear antibodies (ANA) and anti-U ₁ ribonucleoprotein (U ₁ RNP) antibody.

Basic Information

Visiting department

Division of Rheumatology

Common symptoms

Fatigue, fatigue, joint pain, etc.

Contagious

no

Causes of mixed connective tissue disease

The etiology of this disease is inconclusive. Generally speaking, autoimmune theory is recognized, that is, it may be based on genetic immune regulation dysfunction, autoantibodies to the damaged, degraded and mutated components of autoimmune tissue, which may cause immune pathology. The reasons are as follows: the disease and autoimmune diseases have many common manifestations of systemic lupus erythematosus, dermatomyositis and systemic sclerosis; sensitive and specific high titers of anti-U ₁ RNP antibodies, epidermis Ig deposits at the basement membrane, and spotted antinuclear antibodies similar to systemic lupus erythematosus on immunofluorescence examination; antinuclear antibodies were almost all positive, and other serum antibodies such as rheumatoid factor, antinuclear factor, etc. were also partially positive ; In patients with systemic lupus erythematosus, the representative disease of autoimmune disease, some patients can detect anti-U ₁ RNP antibodies.

Clinical manifestations of mixed connective tissue disease

Patients with early disease manifest as fatigue, fatigue, joint pain, Raynaud's phenomenon, swelling or hardening of fingers, inflammatory changes in the lungs, myalgia and muscle weakness, esophageal dysfunction, lymphadenopathy, hair loss, rash, etc. Some patients do not necessarily have multiple clinical manifestations of MCTD at the same time. Overlapping features may appear one after another, and the performance of different patients may vary. In the absence of typical and characteristic clinical manifestations, patients may see a doctor for fever of unknown origin. Patients can show any clinical symptoms that make up the connective tissue disease of the disease.

Examination of mixed connective tissue disease

Serum complement C1q levels are significantly reduced in patients with active mixed connective tissue disease.

Anti-U ₁ RNP antibodies are positive for high titers in mixed connective tissue disease.

Diagnosis of mixed connective tissue disease

Commonly used Sharp standards in clinical practice:

Main criteria

Severe myositis; Pulmonary involvement (less than 70% carbon dioxide diffusion, pulmonary hypertension, and proliferative vascular injury on lung biopsy); Reynolds / esophageal motility reduction; joint swelling, tenderness, or sclerosis of fingers; antinuclear Antibodies were positive, titers> 1: 320, and / or anti-soluble antigen (ENA) antibodies were positive.

2. Minor criteria

hair loss; decreased white blood cell count; anemia; pleurisy; pericarditis; arthritis; trigeminal neuropathy; cheek erythema; thrombocytopenia; mild myositis.

3. Confirmation

4 main criteria; Serological antinuclear antibody is positive, titer> 1: 320, infectious or tumorous diseases need to be excluded.

4. Possible diagnosis

Clinically, there are 3 main standards or 2 main standards and 2 secondary standards; serological antinuclear antibodies are positive, and the titer is> 1: 320.

Treatment of mixed connective tissue disease

The treatment of mixed connective tissue disease is generally based on symptomatic treatment and control of disease development. The treatment plan and drug dosage should pay attention to the principle of individualization, and pay attention to observe the adverse reactions of the drug. Treatment may use different drugs due to certain manifestations of the disease at a certain stage. In general, glucocorticoids have a good effect on arthritis, rash, serositis, myositis, anemia, decreased white blood cell count, and vasculitis. Patients with invasive arthritis without kidney damage can be treated as rheumatoid arthritis. The patients with pulmonary interstitial fibrosis and pulmonary hypertension are often more severe and should be actively treated.