Cluster of differentiation 15 (CD15) is a carbohydrate adhesion molecule. Positive staining for CD15 and negative staining for leukocyte common antigen or other B- or T-cell lineage markers helps recognize Reed Sternberg cells (RSC) in Classical Hodgkin’s Lymphoma (CHL), and distinguishes it from Hodgkin-like neoplasms. CD15 does not stain mesotheliomas and is therefore most useful for distinguishing epithelial mesothelioma from adenocarcinoma.