Polymorphous Light Eruption
Encyclopedia
Polymorphous light eruption (PLE), or polymorphic light eruption (PMLE), is a skin condition caused by sunlight
.
.
Typically, 5-20% of fair skinned populations are affected, but it can occur in any skin type. It is more common in females than in males. The condition can affect all ethnic groups and research suggests that 20% of patients have a family history of the complaint. Those suffering from PLE usually do so by age 30.
The cause of PLE is not yet understood. It is thought to be due to a type IV
delayed-type hypersensitivity
to an allergen produced in the body following sunlight exposure.
One may also purchase clothing that has been tested for its protective qualities.
Some progression to autoimmune disease has been observed.
called afamelanotide
(SCENESSE®) (formerly CUV1647).
Sunlight
Sunlight, in the broad sense, is the total frequency spectrum of electromagnetic radiation given off by the Sun. On Earth, sunlight is filtered through the Earth's atmosphere, and solar radiation is obvious as daylight when the Sun is above the horizon.When the direct solar radiation is not blocked...
.
Types
Two subtypes have been described:- Juvenile spring eruptionJuvenile spring eruptionJuvenile spring eruption is a cutaneous condition that affected the helices of the ears, particularly in boys because their ears are relatively more exposed to sunlight....
- Benign summer light eruptionBenign summer light eruptionBenign summer light eruption is a cutaneous condition, and a name used in continental Europe, and particularly France, to describe a clinically short-lived, itchy, papular eruption particularly affecting young women after several hours of sunbathing at the beginning of summer or on sunny vacations....
Presentation
Symptoms include skin irritations, which may be itchy or painful, and are sometimes confused with hives. These irritations appear upon exposure to sunlight—sometimes only hours after exposure—and may last from 1 to 7 days.Epidemiology
The cases of this condition are most common between the spring and autumn months in the northern hemisphereNorthern Hemisphere
The Northern Hemisphere is the half of a planet that is north of its equator—the word hemisphere literally means “half sphere”. It is also that half of the celestial sphere north of the celestial equator...
.
Typically, 5-20% of fair skinned populations are affected, but it can occur in any skin type. It is more common in females than in males. The condition can affect all ethnic groups and research suggests that 20% of patients have a family history of the complaint. Those suffering from PLE usually do so by age 30.
Causes and prevention
It has been noted that PMLE is caused by an immune reaction to a compound in the skin which is altered by exposure to ultraviolet light. It can be provoked by UVA or UVB rays.The cause of PLE is not yet understood. It is thought to be due to a type IV
Type IV hypersensitivity
Type IV hypersensitivity is often called delayed type hypersensitivity as the reaction takes two to three days to develop. Unlike the other types, it is not antibody mediated but rather is a type of cell-mediated response....
delayed-type hypersensitivity
Hypersensitivity
Hypersensitivity refers to undesirable reactions produced by the normal immune system, including allergies and autoimmunity. These reactions may be damaging, uncomfortable, or occasionally fatal. Hypersensitivity reactions require a pre-sensitized state of the host. The four-group classification...
to an allergen produced in the body following sunlight exposure.
One may also purchase clothing that has been tested for its protective qualities.
Some progression to autoimmune disease has been observed.
Prognosis
Generally, PLE resolves without treatment; also, PLE irritations generally leave no scar.Experimental treatments
In December 2009 Clinuvel Pharmaceuticals Ltd., an Australian pharmaceutical company, released polymorphous light eruption (PLE) Phase III preliminary results with a melanocyte-stimulating hormoneMelanocyte-stimulating hormone
The melanocyte-stimulating hormones are a class of peptide hormones that are produced by cells in the intermediate lobe of the pituitary gland...
called afamelanotide
Afamelanotide
Afamelanotide developed at the University of Arizona is a synthetic analog of the naturally-occurring melanocortin peptide hormone alpha-melanocyte stimulating hormone that has been shown to induce skin pigmentation through melanogenesis and thereby subsequently reduce sun damage to UV exposed...
(SCENESSE®) (formerly CUV1647).