In 1972, Sharp and colleagues described a new autoimmune rheumatic disease
which they called mixed connective tissue disease (MCTD), characterized by
overlapping features of systemic sclerosis (SSc), systemic lupus erythematosus (SLE),
polymyositis/dermatomyositis (PM/DM), high levels of anti-U1snRNP and low
steroid requirement use with good prognosis. MCTD was proposed as a distinct
disease. However, soon after the original description, questions about the existence of
such a syndrome as well as disputes over the features initially described began to
surface. The conundrum of whether MCTD is a distinct disease entity remains
controversial. We undertook a literature review focusing on the articles reporting new
data about MCTD published in the last decade, to determine whether any new
observations help to answer the conundrum of MCTD. After reviewing recent data,
we question whether the term MCTD is appropriately retained, preferring to use the
term “undifferentiated autoimmune rheumatic disease”
