Systemic sclerosis and inflammatory myopathies, which sometimes combine (scleromyositis), have shared pathophysiological elements. In both diseases, many cell subtypes are involved in damage to organs such as T lymphocytes, B lymphocytes, and unconventional (non-B, non-T) lymphocytes called innate lymphoid cell (ILC). The increasing complexity of our understanding of the immune system (multiplication of recognized cell subtypes) also makes the strategies for analyzing pathophysiological mechanisms more complex. Currently, no biomarker perfectly predicts the phenotype and evolution of patients. Multi-OMIC analyzes will be performed (identification of cell populations as well as genomic, transcriptomic and proteomic characterization) in blood and tissue samples (skin and muscle biopsy) in patients with systemic sclerosis and inflammatory myopathies, with the objective of identifying discriminating molecular signatures (biomarkers) according to the characteristics of the disease and its evolution.