PF4 and calcinosis: The antibody response directed to CXCL4 was significantly higher in lsSSc patients with skin involvement, such as typical skin scars called pitting scars, calcinosis (a deposition of insoluble calcium in the skin, associated with longer disease duration), telengiectasia and digital ulcers (DU) (Figure 2a–d) but only in lsSSc [26,27,28].