S100A4 and neoplasm: A growing body of evidence showed that the level of Schwann cell hallmarks, including glial fibrillary acidic protein (GFAP), p75 neurotrophin receptor (p75NTR), S100 calcium‐binding protein A4 (S100A4), was significantly increased in many tumour with PNI, including melanoma,13 breast cancer,14 prostate cancer,15 colorectal cancer.16