Previous studies on immunohistochemical profiling of BLE/APL included D2-40 (16/16), lymphatic vessel endothelial hyaluronan receptor 1 (LYVE1, 2/2), prospero homeobox protein 1 (PROX1, 5/5), CD31 (18/19), CD34 (16/16), factor VIII-related antigen (12/24), WT1 (2/8), and ERG (2/2) [1,8]. The gene discussed is PECAM1; the disease is acute promyelocytic leukemia.