n. [ It. pelle skin + agro rough. ] (Med.) An affection of the skin, characterized by redness, especially in exposed areas, scaling and shedding of the skin, and accompanied with severe gastrointestinal disturbance and nervous symptoms. It is due to a deficiency of niacin (vitamin B3; nicotinic acid) and protein in the diet, and may be caused by malnutrition, or, in some cases, by a heavy dependence on maize for food. It was at one time (ca. 1890) endemic in Northern Italy, and was called Alpine scurvy. It may also be caused by alcoholism or diease causing an impairment of nutrition. It is also called St. Ignatius's itch, maidism, mal de la rosa, mal rosso, and psychoneurosis maidica. A variety of pellagra seen in children is called infantile pellagra or kwashiorkor. [ Stedman ] [ 1913 Webster +PJC ]