CDH11 and systemic sclerosis: Cadherin-11 transcripts found in circulation are associated with established disease and the presence of polyarthritis in RA, as well as with diffuse skin involvement in SSc.13,14 Moreover, preliminary data from our group showed that rare circulating mesenchymal cells can be identified in the peripheral blood of RA and PsA patients using mass cytometry and might be of pathogenetic importance.15 Recently, Orange et al. have identified in the circulation the PRIME cells which are the precursors to inflammatory sublining fibroblasts.16,17