D2-40 identifies a 40 kD O-linked sialoglycoprotein present on a variety of tissues including fetal testes and testicular germ cell tumors. D2-40 has also been demonstrated to react with lymphatic endothelium and is unreactive with vascular endothelium. In neoplastic tissue, immunostaining of lymphatic endothelium by D2-40 has been shown to be useful in identifying lymphatic invasion of primary tumors. This antibody is intended for laboratory use to identify qualitatively by light microscopy D2-40 expressing cells in normal and neoplastic tissues using immunohistochemical (IHC) test methods. Positive results aid in the identification of lymphatic invasion of a variety of cancers.Interpretation must be made within the context of the patient’s clinical history and other diagnostic tests by a qualified pathologist.