PMEL and neoplasm with perivascular epithelioid cell differentiation: However, PEComa has characteristic expression of the melanin markers HMB45 and/or melan A but does not express markers characteristic for HCCC such as CK and squamous epithelium-related markers (e.g., P63, P40, or CK5/6); HCCC generally does not express HMB45, which can help to distinguish it from PEComa.