[Skin associated lympphoid tisues (SALT). Its normal and pathological function].

The skin is a very large organ which covers all the body surface and it is made up of three layers: epidermis and its appendages, dermis and hypodermis. Its main function is that of protection:mechanical protection, function barrier due to its relative impermeability to water and the components dissolved in it, physical protection (sunlight and thermoregulation) and protection against alive agents. This last function is carried out through its own lymphoid system called SALT, formed by cells and humoral compounds with a precise organization. Nevertheless this lymphoid tissues functioning can be altered, thus producing an inflammatory and tumorous pathology.