Recently, Scotece et al. demonstrated that YKL-40 exhibited a sharp increase in skin in response to bleomycin treatment [57], and it has also been previously related to the progression of several inflammatory and fibrotic skin diseases, including systemic sclerosis, dermatitis and pyoderma gangrenosum [58–60]. The gene discussed is CHI3L1; the disease is pyoderma gangrenosum.