In addition to morphological differences, strong S100 protein and negative staining of myogenic markers in most melanomas and clear cell sarcomas (CCS), the presence of specific EWSR1 ATF1 fusion transcripts resulting from t (12:22) (q13; q12) in CCS are helpful features to distinguish the lesions from PEComa. The gene discussed is ATF1; the disease is neoplasm with perivascular epithelioid cell differentiation.