PECAM1 and angiomyolipoma: Special staining for smooth muscle cells, such as actin, desmin, or myosin, and for vascular endothelium, such as factor VIII or CD31 can aid in differentiating angioleiomyoma from haemangioma, angiofibroma, fibroma, angiomyolipoma, and angiomyosarcoma [9].