ASyS and DM present a significant overlap, but also some disease specific differences:patients had similar Mph, T cells (CD4, CD8, TREG), B cells and DC infiltration in the skin• DM: increase in myeloid dendritic cell %• Differences in fibrosis and ILD risk between DM and ASyS could be explained by the increased IL17 production in ASyS. Here, IL17A is linked to dermatomyositis.