Raynaud's phenomenon and initially seronegative mixed connective tissue disease.

We report 2 young women with Raynaud's phenomenon who later developed the laboratory and clinical features of mixed connective tissue disease (MCTD). Antibodies to extractable nuclear antigens were initially negative and remained so far several years before becoming positive. Raynaud's phenomenon is common in MCTD, but laboratory and clinical evidence of the latter may not be present initially.