Extracorporeal Photopheresis (ECP) is a form of apheresis and photodynamic therapy in which the peripheral blood is treated with 8-methoxypsoralen, which is then activated with UV light. ECP is currently a standard therapy for cutaneous T-cell lymphoma (CTCL) and is also effective for graft-versus-host disease (GVHD). The investigators would like to study the outcomes (response rates) of patients receiving ECP treatment and other factors relating to their disease and treatment, as well as procedural events, such as complications.