Background: CD146, also known as melanoma cell adhesion molecule (MCAM) with a molecular weight of 113kDa, is expressed on various human endothelial cells and is involved in tumor angiogenesis and metastasis. It is initially found in malignant melanoma, whereas normal melanocytes do not express it. In addition, CD146 is also widely present in a variety of tissues and tumors. If expressed on intermediate trophoblastic cells, it can be used in combination with other antibodies for the identification of trophoblastic tumors.