NRAS and melanoma: The Ki-67 index often exceeds 8%, and pCK, EMA, and GFAP are negative in PIMM.[9] In recent years, it has been found that the mutation rate of the GNAQ gene in PIMM has been high.[10] Different from malignant melanoma in skin and mucosa, PIMM has a single mutation mode and fewer mutations in BRAF, NRAS, and KIT genes.