From Italian pelle agra, sour or perhaps rough skin and this from Latin pellis aegra, sick skin. Skin disease with discoloration and roughness especially in areas exposed to the sun with digestive and nervous alterations, caused by the lack or poor digestive absorption of niacin, of the vitamin group B . It has also been called rose sick, Asturian leprosy, Lombardy leprosy, scurvy from the Alps. . .