Mixed connective tissue disease--goodbye to all that.

Since it was first described mixed connective tissue disease (MCTD) has been the subject of much debate. In particular the question of whether it is a truly distinctive disease entity has been challenged. It seems clear that the original description of MCTD as a mild disorder, rarely affecting the lungs or kidneys and requiring small doses of corticosteroids only, is no longer tenable. In this review a historical analysis of the clinical and serological features is presented. It is suggested that the concept of MCTD as a distinct disease entity is better replaced by the term 'undifferentiated autoimmune rheumatic/connective tissue disorder'. Many of these patients will later 'convert' into scleroderma or lupus; some will remain undifferentiated.