Autoimmune disease: A disease in which the immune system destroys or attacks a person's own tissues.
Chronic: Long-lasting, ongoing.
Dermis: The layer of skin beneath the epidermis.
Emollient: A substance composed of fat or oil that soothes and softens the skin.
Epidermis: The outermost layer of skin.
Exfoliation: Peeling and sloughing off of the skin's tissue cells.
Gene: A unit of inheritance that contains the instructions, or code, that a cell uses to make a specific product, usually a protein. Genes are made of a substance called DNA. They govern every body function and determine inherited traits passed from parent to child. This code is passed on to our children.
Genetics: The science of understanding how diseases, conditions, and traits are inherited.
Inflammation: A characteristic reaction of tissues to injury or disease. It is marked by four signs: swelling, redness, heat, and pain.
Human leukocyte antigen (HLA): Immune system markers strongly associated with the causes(s) of psoriasis.
Immune response: The reactions of the immune system to foreign substances.
Immune system: A complex network of specialized cells and organs that work together to defend the body against attacks by foreign substances, such as bacteria and viruses.
Infection: The invasion of the body by microorganisms that reproduce and multiply, causing disease.
Koebner’s phenomenon: Psoriatic lesions appear at the site of injury, infection or other skin problem. The lesion may mark the initial onset of psoriasis or maybe a new lesion in an existing case of psoriasis.
Lesions: A wound or injury to the skin.
Plaques: Plaque is a flattish raised patch on the skin. Psoriatic plaques are patches of thickened and reddened skin that are covered by silvery scales.
Predisposed: Susceptible, likely to get.
Psoriasis: A chronic (long-lasting) skin disease characterized by scaling and inflammation. Scaling occurs when cells in the outer layer of skin reproduce faster than normal and pile up on the skin's surface. Possibly a disorder of the immune system.
Psoriatic arthritis: Joint inflammation that occurs in about 10 percent of people with psoriasis.
Scales: Thin flakes on the skin surface.
Steroid: An abbreviated word for corticosteroids, which are powerful drugs used to control inflammation and itching of the skin.
Systemic: Pertaining to the body as a whole.
T cell: A type of white blood cell that is part of the immune system and normally helps protect the body against infection and disease. In psoriasis, it also can trigger inflammation and excessive skin cell reproduction.
Topical: On the skin.
Trigger: Environmental factors that act together with a genetic predisposition to cause the onset or worsening of psoriasis. Injuries and infections are common triggers.
Ultraviolet light: The part of sunlight that has a short wavelength and encompasses the wavelengths that treat psoriasis. This type of light can also cause sunburn.