Mixed connective tissue disease (MCTD) is a rare disorder, that shows features of rheumatoid arthritis, SLE, polymyositis and systemic sclerosis and that is characterized by anti-ribonucleoprotein antibodies in high titre.
The clinical picture is variable and changes over time, often towards the clinical picture of systemic sclerosis.
Most patients are women aged 30-40 years.
Clinical picture
Almost all patients have arthritis or arthralgia
Swelling of the fingers and Raynaud's phenomenon
Skin changes resembling those seen in SLE
Muscle symptoms, which resemble those seen in polymyositis
Pleuritis, carditis and nephritis occur but are more common in SLE
Examinations and diagnosis
Full blood count, ESR, CRP, chemical urinalysis, plasma creatinine, creatine kinase, serum antinuclear antibodies, rheumatoid factor
Anaemia, leucopenia and thrombocytopenia are common findings.
ESR is usually elevated, but CRP concentration may be normal or slightly elevated.
Speckled pattern of anti-nuclear antibodies is a typical finding
Within specialized care e.g. determination of antibodies against extractable nuclear antigens: antibodies reacting with nuclear ribonucleoprotein are found. The diagnosis is made within specialized care.