Solar dermatitis is an inflammatory reaction of the skin, induced by sunlight and proceeding according to the type of allergic reaction. Solar dermatitis is manifested by redness and puffiness of the skin, the appearance of rashes on it by the type of urticaria. The disease can recur, acquire a chronic course, transform into eczema. In the diagnosis of solar dermatitis, examination, dermatoscopy, photoallergic tests, hormonal and metabolic studies, kidney and liver examinations are used. Therapy of solar dermatitis is carried out with glucocorticoid ointments, anti-inflammatory and antihistamines.
ICD 10
L56.2 L56.3 L56.4 L56.8
General information
Solar dermatitis (photodermatitis, solar allergy) is one of the many variants of actinic dermatitis. It develops only in some people and is caused not so much by the intensity of solar irradiation as by the individual reactivity of the body. Solar dermatitis is observed more often in adults who have a history of indicating any allergic reactions (contact allergic dermatitis, pollinosis, allergic rhinitis, etc.) or a hereditary predisposition to them.
The allergic reaction that occurs with solar dermatitis is of a delayed type. This means that the symptoms of the disease manifest themselves with repeated exposure to the provoking factor, against the background of already existing sensitization of the body.
Causes
The sun’s rays themselves are not an allergen. Solar dermatitis develops when exposed to photosensitizers — substances that increase the sensitivity of the skin to ultraviolet radiation. Under the action of UV rays, these substances release free radicals that react with body proteins. As a result, new compounds are formed, which act as antigens, triggering the entire mechanism of an allergic reaction. Depending on the nature of photosensitizing substances, dermatology identifies external and internal causes of solar dermatitis.
External (exogenous) causes include photosensitizing substances that fall directly on the skin. These can be household chemicals, medications for external use, cosmetics (musk of aftershave lotions, benzocaine in soap, benzophenones of sunscreens), plant juice (meadow grasses, hogweed).
Internal (endogenous) causes of the development of solar dermatitis may be substances that accumulate in the body during metabolic abnormalities (obesity, diabetes mellitus); systemic drug treatment; disorders in the work of organs that neutralize and remove toxic substances (chronic hepatitis, cirrhosis of the liver, chronic constipation, kidney failure, etc.).
Symptoms
The onset of photodermatitis can be observed after a short stay under sunlight or other sources of UV rays (for example, in a solarium). Redness and swelling, resembling a grade I burn, are noted on the exposed skin areas. The process is accompanied by a pronounced itching and burning sensation. Then, numerous small rashes appear on the reddened areas, the elements of which are similar to urticaria. It is possible to spread rashes to areas of the skin that have not been in contact with UV rays. Solar dermatitis can occur against the background of deterioration of well-being and be accompanied by cheilitis and / or conjunctivitis.
Rashes of solar dermatitis pass within 2-3 weeks, but with repeated exposure to ultraviolet light they may appear again. Further exposure to UV rays without removing the causal photosensitizing substance from the body can lead to the development of a chronic form of solar dermatitis. It is manifested by an increase in the skin pattern, infiltration and dryness of the skin, the appearance of hyperpigmentation and vascular asterisks.
A separate clinical form of solar dermatitis is persistent solar erythema, in which redness of the skin and rash persist for several months or years. Her symptoms do not go away after the photosensitizing factor is eliminated and intensify after another exposure to sunlight.
Diagnostics
If a rash appears on the skin after sunburn, a dermatologist’s consultation is necessary. Detection of photosensitization during the patient’s interview, dermatological examination and dermatoscopy of rashes allow the doctor to make a presumptive diagnosis. The photosensitizing substance is determined when applying application samples with photoallergens. Allergens are applied to the skin in 2 rows, after which a bandage is applied to the examined area of the skin. A day later, one row is subjected to UV irradiation, and the second remains the control.
Identification of endogenous causes of the development of solar dermatitis may require biochemical analysis of blood and urine, Zimnitsky’s test, hormonal studies, ultrasound and CT of the kidneys, excretory urography, ultrasound of the abdominal cavity. To exclude systemic lupus erythematosus, an antinuclear factor, lupus anticoagulant, and C-reactive protein can be determined in the blood. Differential diagnosis of solar dermatitis is carried out with solar erythema, lichen planus, erysipelas, superficial form of SLE, other types of dermatitis: atopic, radiation, allergic contact dermatitis.
Treatment
Photodermatitis therapy consists in limiting the patient’s exposure to the sun and eliminating the causal factor. Ointments with corticosteroid drugs (triamcinolone, betamethasone), anti-inflammatory drugs (ibuprofen, diclofenac), antihistamines (hifenadine, loratadine, chloropyramine), B vitamins, chloroquine, etc. are used in the treatment. Patients may be recommended treatment by a gastroenterologist, endocrinologist or nephrologist.
Treatment of persistent solar erythema is carried out by systemic administration of glucocorticoids. In severe cases and if there are contraindications to glucocorticoid therapy, cytostatics (azathioprine, cyclophosphamide) may be prescribed. Patients need careful protection from ultraviolet radiation.