Rare systemic autoimmune disease with an overlapping feature of at least two connective tissue diseases

Clinical features

• Initially non-specific - arthralgia, malaise, myalgia, low-grade fever
• Skin: Raynauds, sclerodactyly
• Joint: joint involvement usually more severe than SLE, arthritis with deformities similar to RA an also occur
• Muscles: inflammatory myopathy clinically and histologically similar to polymyositis often manifests as myalgia and is a common symptom
• Lung: pulmonary involvement occurs in almost 73% of patients, and dyspnoea is the most common symptom
  • Pulmonary manifestations may include pleural effusion, pulmonary arterial hypertension, interstitial lung disease (ILD), pulmonary vasculitis, thromboembolic disease, alveolar hemorrhage, infections, and obstructive airway disease
• Heart: pericarditis
• Renal: renal involvement occurs in 15 to 25% of patients

Investigations

• Bloods:
  • FBC - anemia, leukopenia
  • Hypergammaglobulinemia
  • Raised inflammatory markers
• Antibodies: anti-RNP, rheumatoid factor, anti-CCP
• Imaging: may be used to look for organ involvement

Management

• Varies according to presentation
• CCBs may be helpful for Raynaud’s
• If there is significant muscle or lung disease immunosuppression may be required
• Monitoring - patients should be monitored for pulmonary hypertension (annual echo) and ILD (PFTs)