In research from 2018 [18], it is mentioned that malignant melanomas having the colon as a starting point are only scarcely encountered (less than 40 cases reported), and that, when histopathological analysis of the surgical specimen suggested malignant melanoma, immunohistochemical analysis confirmed it with testing for the S100 protein, Melan-A, HMB-45, and vimentin. The gene discussed is PMEL; the disease is melanoma.