Positive staining of tumor-stage Kaposi sarcoma with lymphatic marker D2-40

BackgroundKaposi sarcoma (KS) is a vascular tumor first described by Moritz Kaposi (Kohn) in 1872 and recently linked to human herpesvirus 8. All forms of KS share the same pathologic features, including atypical spindle cells and slitlike vascular spaces. The exact origin of the neoplastic endothelial cells (vascular vs lymphatic) has recently been debated.ObjectiveWe sought to further investigate the origin of neoplastic cells in KS.MethodsD2-40, a novel monoclonal antibody to a sialoglycoprotein that reacts with a fixation-resistant epitope in lymphatic endothelium, was used to investigate possible lymphatic origin of neoplastic cells in KS.ResultsWe report 5 cases of tumor-stage KS that showed positive staining with lymphatic marker D2-40.LimitationsSmall study size is a limitation.ConclusionThe origin of neoplastic cells in KS may be lymphatic or mixed lymphatic and vascular. Further studies are needed to elucidate the exact origin of neoplastic cells in KS.