CD63 (Cluster of Differentiation 63) is a member of the family of tetraspan moieties. It has a diverse distribution on the surface and in the cytoplasm of many cell types including lymphoid, myeloid, endothelial cells and melanoma. This antibody is useful in identifying malignant melanoma and in differentiating renal oncocytomas (RO) from eosinophilic renal cell carcinomas (eRCC).