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Mixed Connective Tissue Disease (MCTD)

MCTD was first described by Sharp and co-workers in 1972. It is an overlap syndrome characterized by a combination of manifestations similar to those seen in systemic lupus erythematosus (SLE), Systemic Sclerosis (SSc), and inflammatory myositis similar to polymyositis (PM). Some patients may develop an erosive arthritis similar to rheumatoid arthritis (RA). The diagnosis requires the presence of high titer anti-U1-RNP antibodies, which causes a high titer, speckled antinuclear antibody (ANA). These patients lack other specific autoantibodies such as anti-Sm, anti-SS-B, anti-double-stranded (ds) DNA, and anticentromere.

MCTD is 15 times more common in women than men. The mean age at diagnosis is 37 years, with a range of 4 to 80 years. There is no apparent racial or ethnic predisposition.

Clinical manifestations of MCTD:

The onset of MCTD is characterized by features of SSc, SLE, PM, and RA that occur simultaneously but usually develop sequentially over time. The most common manifestations at onset are:

  • Raynaud's phenomenon (>90%).

  • Synovitis (>90%).

  • Swollen hands with puffy fingers (>70%).

  • Myositis (>50%).

Common gastrointestinal manifestations:

The most common gastrointestinal (GI) manifestations are similar to those of scleroderma: upper and lower esophageal sphincter hypotension with gastroesophageal reflux heartburn/dyspepsia (60% to 70%), esophageal dysmotility and/or stricture with dysphagia (40%), and pulmonary aspiration. Esophageal function is abnormal in up to 85% of patients, although it may be asymptomatic. Small bowel and colonic disease is less common in MCTD than in scleroderma. Other less common GI complications include intestinal vasculitis, acute pancreatitis, and chronic active hepatitis.

Common nervous system manifestations:

Severe central nervous system involvement is unusual with MCTD. Trigeminal neuralgia is the most common problem, as it occurs in progressive systemic sclerosis. Sensorineural hearing loss is reported.

Pulmonary Manifestations of Mixed Connective Tissue Disease

Symptoms

  • Dyspnea

15% to 20%

  • Chest pain and tightness

7%

  • Cough

5%

Chest X-ray findings

  • Interstitial changes/NSIP

15% to 30%

  • Small pleural effusions

5% to 10%

  • HRCT scan findings

  • Interstitial lung disease/NSIP

66%

Pulmonary function studies

  • Restrictive pattern

69%

  • Decreased carbon monoxide diffusion

66%

Pulmonary hypertension

23% to 30%


HRCT, High-resolution computed tomography; NSIP, nonspecific interstitial pneumonitis.

Laboratory Findings in Patients With Mixed Connective Tissue Disease

ABNORMALITY

FREQUENCY (%)

Anemia

65 to 75

Leukopenia/lymphopenia

57 to 75

Hypergammaglobulinemia

80

Rheumatoid factor

50

Antinuclear antibody (>1:1000)

100

Anti-U1-RNP

100

Hypocomplementemia

25


Pubmed

UpToDate

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Web:

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Arthritis Foundation