Patients with active disease who had three or more skin regions (legs, trunk, arms, head, and neck) covered with a rash had higher S100A8/A9 serum levels than those with a rash in two or less regions (no rash: 5409 ± 0 ng/mL; rash in one region: 5577 ± 3556 ng/mL; rash in two regions: 5136 ± 2765 ng/mL; rash in three regions: 6631 ± 3448 ng/mL; rash in four regions: 9027 ± 2158 ng/mL; R2 = 0.09, p = 0.0376) (Figure 6). Here, S100A8 is linked to exanthem.