Immunohistochemical (IHC) testing for melanin markers (the group typically includes HMB-45, Melan-A/MART-1, and MITF) aims to detect specific antigens associated with melanin-producing cells (melanocytes). These markers are primarily used to diagnose malignant melanoma, both in the skin and in metastases, and to differentiate it from other pigmented or spindle cell/localized tumors that may mimic it.