Mixed Connective Tissue Disease (MCTD)/Collagen Overlap Syndromes
Chronic inflammatory autoimmune disease characterised by overlapping clinical features of SLE, scleroderma, polymyositis or dermatomyositis and maybe rheumatoid arthritis – often have laboratory feature of high levels of antibodies to RNP. The existence of MCTD as a diagnosis is not universally accepted.
F 15x> M; mean age of diagnosis around 37 years (range 5 years to 80 years). More common than systemic sclerosis and polymyositis, but less common than SLE.
Another form – undifferentiated connective tissue disease (UCTD) is also recognised – may be a form of connective tissue disease that has not developed to the point of being easily identified some may not develop or go into remission. Overlap syndromes occur when enough of the clinical features to be diagnosed as one particular form of connective tissue disease, but also have some features of another distinct connective tissue disease – this could happen in up to 25% of those with a connective tissue disease.
Clinical features of MCTD:
Have features of SLE, scleroderma, polymyositis or dermatomyositis and maybe rheumatoid arthritis; commonly have oedema of hands and swelling of fingers (no erosions found), synovitis, myositis, Raynauds phenomenon (very common and often precedes other symptoms); acrosclerosis; oesophageal dysmobility; lymphadenopathy
Renal and/or CNS involvement is rare.
Arthritis of small joints of hand and foot and wrist is common – joint symptoms are the most common initial presentation of MCTD.
High anti-RNP antibodies (U1 RNP); increased ESR; mild leuckopenia
NSAID’s often adequate; analgesics; corticosteroids if have myositis or lung involvement; immunosuppressives.