Mixed Connective Tissue Disease

• Anti-ribonucleoprotein (RNP) antibody positivity is necessary for diagnosis.
• Antinuclear antibody positive in all. (view image)
• If meets criteria of a different rheumatologic disease, consider overlap diagnosis.

• Systemic lupus erythematosus
• Systemic sclerosis
• Idiopathic inflammatory myopathy
• Rheumatoid arthritis
• Primary Raynaud’s
• Idiopathic pulmonary hypertension
• Undifferentiated connective tissue disease

Treatment depends on disease manifestations and requires collaborative care.

• Raynaud’s: Avoiding triggers, calcium channel blockers, topical nitroglycerin applied to the interdigital web spaces, PDE-5 inhibitors, SSRIs, and in severe cases, PDE-5 inhibitors or vasodilators like iloprost
• Arthritis: Disease-modifying anti-rheumatic drugs (DMARDs)
• Myositis: Immunomodulating medications like mycophenolate, methotrexate, IVIg, rituximab, etc.
• Sclerodactyly: Mycophenolate, etc., along with collaboration with dermatology
• Interstitial lung disease: azathioprine, mycophenolate, or rituximab
• For inflammatory manifestations, a prednisone taper is often required while waiting for other medications to take effect.

• Can evolve over time into another connective tissue disease. Raynaud’s tends to be severe and can progress to ulcerative lesions.
• Systemic sclerosis-like manifestations typically cause the most long-term morbidity and mortality.
• Pulmonary hypertension is a major cause of mortality.
  • PFTs and echos can help screen for ILD and PAH.

• Systemic rheumatic disease with features of lupus, rheumatoid arthritis, systemic sclerosis, and/or myositis
• Raynaud’s phenomenon present in almost all patients (view image)
• Ribonucleoprotein (RNP) positivity is necessary for diagnosis:
  • High-titer RNP=serological hallmark
• ANA negativity doesn’t rule out MCTD but makes MCTD incredibly unlikely diagnosis.
• Pulmonary HTN: major cause of mortality