FCN1 and systemic sclerosis: In addition, the different compositions of cell subtypes in different tissues of the same disease such as macrophages divided into FABP4+, SPP1+ and FCN1+ macrophages in SSc lungs [70], while macrophages mainly consisted of CCR1+, MARCO+ and TREM2+ macrophages in SSc skin[73], makes it possible to provide targeted treatment plans for different clinical manifestations.