Immunohistochemical assay for coagulation factor VIII (Factor VIII - Related Antigen / von Willebrand Factor - vWF) aims to detect this protein, which is produced and stored in vascular endothelial cells and platelets. It is used as a sensitive and specific marker for identifying and staining endothelial cells in tissues and is an important tool in the diagnosis of hemangiomas and in assessing tumor vascular density (angiogenesis).