The clinical impact of Anti-DFS70 antibodies in undifferentiated connective tissue disease: case reports and a review of the literature.

Anti-nuclear antibody (ANA) positivity suggests CTD but can also lead to a diagnosis of UCTD when a patient does not fulfill the CTD diagnostic criteria. An anti-dense fine speckled (DFS) immunofluorescence (IIF) pattern can be observed when using an ANA test on HEp-2 cells and is due to the presence of antibodies to the nuclear DFS70 antigen that has rarely found in CTD. Serological testing for anti-DFS70 antibodies could therefore play a very interesting negative predictive role in stratifying patients on the basis of the evolution of UCTD to CTD. We described two patients ANA and anti-DFS70 positive in which the use of new method allowing the immunoadsorption of anti-DFS70 antibodies has permitted to exclude the incorrect diagnosis of CTD.