Although PEComas and clear-cell sarcoma of soft tissue share some phenotypic features, including positive reactivity to the melanocytic marker HMB-45 and Melan-A, clear-cell sarcoma of soft tissue exhibits dense fibrous septae rather than the delicate vascular-rich stroma of the PEComas. The gene discussed is PMEL; the disease is neoplasm with perivascular epithelioid cell differentiation.