[Extracorporeal photopheresis in dermatology]

Extracorporeal photochemotherapy or photopheresis is an immunomodulatory therapy that combines leukapheresis with phototherapy. Blood from the patient is processed to give a leukocyte-rich plasma, which is then treated ex vivo with a photosensitizer and ultraviolet A radiation before reinfusion back into the patient. The exact mechanism of action of photopheresis has not been fully elucidated although it is thought that induction of leukocyte apoptosis and formation of dendritic cells is essential for the development of an immune response to pathogenic cells. Extracorporeal photophoresis was initially used for treating cutaneous T-cell lymphoma. Since then, in view of its efficacy and safety, it has been used in a number of cutaneous and noncutaneous diseases with uneven results, which can in part be explained by the different patient selection criteria, therapy regimens, and follow-up protocols used in different hospitals.