Mixed Connective Tissue Disease
Mixed connective tissue disease is a systemic autoimmune overlap condition in which a patient develops a characteristic combination of features from several connective tissue diseases, particularly SLE, systemic sclerosis and inflammatory myositis.
Causes and Risk Factors
The exact underlying cause is unknown.
Risk factors include: [Ref]
- Females
- Genetic factors
Clinical Features and Diagnosis
Mandatory criteria: [Ref]
- +ve Anti-U1-RNP antibodies, PLUS
- Raynaud phenomenon or diffuse oedema of the fingers or hand oedema
Additional findings: [Ref]
- Clinical features / manifestation
- Synovitis
- Myositis
- Oesophageal dysmotility → reflux, dysphagia
- Pleuritis
- Pericarditis
- Interstitial lung disease
- Leukopaenia
- Serology
- +ve ANA in most patients
- +ve Anti-SMN complex antibodies in ~40% of patients
Complications
Most common cause of death: pulmonary hypertension [Ref]
Other serious complications include: [Ref]
- Interstitial lung disease
- Infections
Management
There is no single disease-modifying therapy for mixed connective tissue disease. Immunosuppressants are not routinely used.
Management is entirely symptom-driven, targeting the affected organs: [Ref]
- Interstitial lung disease → mycophenolate mofetil
- Pulmonary hypertension → vasodilators (e.g. sildenafil) + immunosuppressants (e.g. corticosteroids and cyclophosphamdie)
- Raynaud phenomenon → calcium channel blocker
- Arthritis → NSAIDs and hydroxychloroquine
- Pleuritis / pericarditis / myositis → steroids
- GI symptoms → PPIs or H2 receptor antagonist