Solar polymorphic eruption
The Solar polymorphic eruption is the most common disorder among idiopathic photodermatoses, it affects the skin that is being exposed to sunlight and it is characterized for a morphology that in general is pruritic and papular, temporal and recurrent. The prevalence of this condition depends on the race, therefore it can be found in about twenty six percent of the population of Caucasian European.
The Solar polymorphic eruption affects more commonly to women, especially to those located on latitudes more closely to Ecuador. About fifty percent of the cases are manifested during the first two decades of life, it appears from childhood to adult age, but generally it is manifested in young adults.
The clinical form that is most common is the classic papular, which consists in the emergence of an erythematous papular eruption which starts with small papules which tend to grow and compromise bigger areas. They produce a burning and pruritic sensation. There can also be found the emergence of papulovesicles erythematous papules, erythematous plaques, and nodules. Generally one type of lesion prevails. These lesions usually emerge during spring and they tend to disappear during the summer, but they can also persist and progress during summer, in severe cases the condition exacerbates during winter due to an exposition of skin to sunlight. In general a sprout takes weeks to be healed. This condition turns out to be chronic, just in a minority the condition remits spontaneously.
The Solar polymorphic eruption has relapses indefinitely but it can also disappear spontaneously. Histologically there can be observed a dense perivascular lymphocytic infiltrate on the papillary and medium dermis. On the epidermis it presents spongiosis.
There are two morphologic types that are less frequent: chronic solar polymorphic eruption with a hemorrhagic plaque, papulovesicular solar polymorphic eruption, and the solar polymorphic eruption without eruptions. Generally the condition begins t present symptomatology one or two days after the exposition to sunlight, although some individuals present symptoms just a few hours after the exposition to sunlight.
Zones that are mostly affected are located on face, neck, upper extremities on their internal face, and in less proportion lower extremities. Areas that aren’t affected usually include the scalp, infranasal region and retroauricular region. There can be absence of compromise on areas that are exposed to sunlight, such as hands, although this phenomenon is not specific of solar polymorphic eruption.
It is known that patients affected by this condition are affected by photo sensibility which is mainly increased for ultraviolet radiation type A ; although they can also be sensitive to ultraviolet radiation type B, or to both of them. For the diagnosis the lesions can be reproduced by exposing the patient skin to ultraviolet radiation. The cause for solar polymorphic eruption is unknown, although histological, clinical and immunological parameters suggest a response of cellular hypersensitivity. There has not been identified a specific antigen. Part of the treatment for solar polymorphic eruption consists on photo-protection with adequate clothes and sunscreens and the use of antimalarials.