Overlap syndromes

Diagnostic criteria of Alarcon-Segovia and Villareal[22]Alarcon-Segovia D, Villareal M. Classification and diagnostic criteria for mixed connective tissue disease. In: Kasukawa R, Sharp GC, eds. Mixed connective tissue disease and anti-nuclear antibodies. Amsterdam, the Netherlands: Elsevier; 1987:33-40.

Mixed connective tissue disease (MCTD) is defined by:

• Serologic criteria: positive anti-U1 ribonucleoprotein (U1 RNP) passive hemagglutination titer greater than or equal to 1:1600 and

• Clinical criteria: three of the following clinical findings, at least one of which must be either synovitis or myositis:

  • Edema of the hands

  • Synovitis

  • Myositis

  • Raynaud phenomenon

  • Acrosclerosis.

Diagnostic Criteria of Kasukawa et al[23]Kasukawa R, Tojo T, Miyawaki S, et al. Preliminary diagnostic criteria for classification of mixed connective tissue disease. In: Kasukawa R, Sharp GC, eds. Mixed connective tissue disease and anti-nuclear antibodies. Amsterdam, the Netherlands: Elsevier; 1987:41-7.

Definitive diagnosis of MCTD requires:

• One or two common symptoms: Raynaud phenomenon and/or swollen fingers of hands

• Positive anti-U1 RNP

• One or more findings in at least two of the following disease categories:

  • Systemic lupus erythematosus-like findings: polyarthritis, lymphadenopathy, facial erythema, pericarditis or pleuritis, leukopenia, or thrombocytopenia

  • Systemic sclerosis-like findings: sclerodactyly, pulmonary fibrosis (restrictive changes of the lung, or reduced diffusing capacity of the lung for carbon monoxide), hypomotility, or dilation of esophagus

  • Polymyositis-like findings: muscle weakness, increased creatine kinase, myogenic pattern in an electromyogram.