ACTA1 and neoplasm with perivascular epithelioid cell differentiation: The preliminary microscopic diagnosis was “angiomatous proliferation with epithelioid large cells resembling PEComa.” In order to better define the nature of the tumour, a panel of histochemical and immunohistochemical staining was performed, including Perls' Prussian blue and Schmörl techniques, CD 31, CD 34, Desmin, α-SMA, Vimentin, Cytokeratins AE1/AE3, CK8/18, Chromogranin-A (CgA), CD 10, HMB45, Melan A, and S100 protein.