D2-40 is only expressed in lymphangiomas and some malignant vascular tumors, which is not difficult to diagnose in combination with the above indicators.[11] The tumor cells expressed CD31 and CD34 (vascular +) and D2-40 (lymphatic +), and the pathological diagnosis of hemolymphangioma was definite. The gene discussed is PECAM1; the disease is lymphangioma.