A delayed hypersensitivity involving the reaction between sunlight or other radiant energy source and a chemical substance to which the individual has been previously exposed and sensitized. It manifests as a papulovesicular, eczematous, or exudative dermatitis occurring chiefly on the light-exposed areas of the skin.

A nonimmunologic, chemically induced type of photosensitivity producing a sometimes vesiculating dermatitis. It results in hyperpigmentation and desquamation of the light-exposed areas of the skin.

A chronic inflammatory genetically determined disease of the skin marked by increased ability to form reagin (IgE), with increased susceptibility to allergic rhinitis and asthma, and hereditary disposition to a lowered threshold for pruritus. It is manifested by lichenification, excoriation, and crusting, mainly on the flexural surfaces of the elbow and knee. In infants it is known as infantile eczema.

Any inflammation of the skin.

A contact dermatitis due to allergic sensitization to various substances. These substances subsequently produce inflammatory reactions in the skin of those who have acquired hypersensitivity to them as a result of prior exposure.