What is Actinic Prurigo?
Actinic prurigo (AP) is a rare skin condition that mainly affects areas of the skin exposed to sunlight, like the face, neck, and upper extremities. However, it can also occur on parts of the skin that aren’t usually exposed to the sun, such as the buttocks. This skin condition usually starts in the spring with very itchy, symmetric bumps and lumps on the skin, and can continue until the winter months.
In serious situations, it can lead to skin scratching, inflammation of the lips, eye diseases and scarring. Actinic prurigo is usually found in young girls before they reach puberty, but can occur in anyone, regardless of their age or gender. It’s more common in Native American populations across North, Central, and South America, and is thought to have a strong link to genetics.
To diagnose actinic prurigo, doctors typically rely on physical examination. The first step in managing this skin condition is to protect the skin from the sun and avoid exposure. Treatment usually involves skin creams that can reduce itching or inflammation, UV-light therapy (photochemotherapy) for more severe cases, and other medications that work throughout the body. If it’s not treated, actinic prurigo can continue into adulthood and becomes a long-term condition.
What Causes Actinic Prurigo?
The exact cause of actinic prurigo, a type of skin disease, is not fully known, but it seems to be influenced by genetics. This suggests it could be an autoimmune condition, where the body mistakenly attacks its own cells. Specifically, a variation of the human leukocyte antigen DR4, a specific type of gene, is found in 90% of people with this condition. The subtype DRB1*0407 of this gene is seen in 60% of cases.
Apart from these genetic factors, exposure to environmental elements, particularly ultraviolet light, seems to strongly trigger the disease. Older research suggests that this condition is more common in people living in high-altitude areas, where UV light is stronger. If a person with this condition moves to a place at a lower altitude, it has been noted that the severity of the disease improves.
Risk Factors and Frequency for Actinic Prurigo
Actinic prurigo, a certain type of skin condition that is triggered by sun exposure, is unusual in the United States but relatively more prevalent among American Indians in North, Central, and South America. It can affect anyone, regardless of their gender, but it is often observed in female patients. Age doesn’t seem to matter – the condition can occur at any stage of life, but it’s usually seen in individuals who haven’t reached puberty, with the average age being below 10 years. A specific pattern seems to emerge with this condition as it tends to occur more in regions that are dry, warm, and situated at least 1,000 meters above sea level.
Signs and Symptoms of Actinic Prurigo
Actinic prurigo is a skin condition often appearing in early spring when people start spending more time in the sun. The disorder causes intensely itchy skin bumps with redness, mainly appearing on areas exposed to sunlight like the face, neck, and arms, but they can also develop on the body parts usually covered by clothing, such as the buttocks. Other skin changes may include thickening, scarring, and changes in color due to constant itching.
One specific symptom associated with actinic prurigo is actinic cheilitis, a lip inflammation due to sun exposure. This may occur alone or together with the widespread skin bumps.
- Intensely itchy skin bumps with redness
- Often appear on sun-exposed areas, such as face, neck, and arms
- Can also appear on less exposed areas like the buttocks
- May cause skin thickening, scarring, and changes in color
- Actinic cheilitis, a lip inflammation caused by sun exposure, may also occur
Testing for Actinic Prurigo
Actinic prurigo, a skin condition, is usually diagnosed by a doctor through a detailed discussion of the patient’s health history and a physical examination. Patients typically describe severe itching, red skin bumps that appear in spring or summer. Interestingly, some patients may not relate the start of these symptoms to sun exposure.
The diagnosis can be supported by several additional tests. These include skin exposure to light under controlled conditions (photo-testing), microscopic examination of skin tissue (histologic evaluation), and a genetic test looking for a specific variation (allele) known as HLA DR4.
Doctors often also conduct lab tests and examine the skin using a technique called immunofluorescence. These help them rule out other diseases that react to light, such as lupus erythematosus, and other conditions that may look similar to actinic prurigo.
Treatment Options for Actinic Prurigo
For minor cases of actinic prurigo, a skin condition triggered by exposure to sunlight, the recommended treatment focuses on avoiding sunlight. This involves spending more time indoors or in shaded areas, wearing sun-protective clothing such as sunglasses and wide-brimmed hats, and using a sunscreen that protects against a wide range of harmful sun rays. Medications such as topical corticosteroids and non-drowsy antihistamines can help soothe symptoms during acute episodes.
However, more severe and ongoing cases may require more robust treatments like antimalarial medications, tetracyclines, and systemic corticosteroids – drugs that decrease inflammation and suppress the immune system.
Thalidomide, a potent medication, is often the go-to treatment for severe actinic prurigo cases that don’t respond to other treatments. Despite its effectiveness, it can cause serious side effects including nerve damage and birth defects. Therefore, it is not recommended for pregnant women or those planning to conceive soon. Women who are of childbearing age should use contraception while on this drug. It’s also important for doctors to test for potential nerve damage before the treatment begins and monitor patients throughout the treatment process.
Other treatment options include immunosuppressive medications like cyclosporine A and photochemotherapy (therapy with psoralen and ultraviolet A, or PUVA). Both of these treatments have shown positive results in managing symptoms of actinic prurigo and treating skin changes caused by the condition.
What else can Actinic Prurigo be?
Actinic prurigo was once believed to be a type of skin condition caused by sunlight known as polymorphous light eruption (PMLE). However, research involving genetic testing and looking closely at the unique signs and symptoms of actinic prurigo now suggest that these are two separate skin conditions triggered by sunlight. A gene variant, specifically the HLA-DR4 allele, subtype DRB1*0407 is strongly linked with actinic prurigo but not with PMLE.
Actinic prurigo usually develops at a younger age and often presents with symptoms like chapped or cracked lips (cheilitis) and sometimes inflammation of the eye (conjunctivitis), symptoms which are never seen in patients with PMLE. When a doctor suspects actinic prurigo, they will also run laboratory tests to exclude other similar conditions such as lupus erythematosus – a long-term inflammatory condition causing pain and redness and porphyria – a group of disorders that can cause nerve and skin problems. So in summary:
- Polymorphous light eruption is not the same as actinic prurigo
- Systemic lupus erythematosus is another condition to be ruled out
- Porphyria, a group of disorders, is also another differential diagnosis
What to expect with Actinic Prurigo
Actinic prurigo is a long-term condition that can flare up again with recurrent exposure to the sun. Treatments like thalidomide and cyclosporine A, which are drugs that suppress the immune system, have been found to be helpful in managing symptoms over the long term.
Interestingly, some teenagers might experience a relief of symptoms on their own, which means their condition may not worsen or continue into their adult years.
Possible Complications When Diagnosed with Actinic Prurigo
Possible issues that can happen due to actinic prurigo, a skin condition, are:
- Secondary bacterial infections
- Contact dermatitis
- Impetigo
Preventing Actinic Prurigo
It is essential for patients to understand the need to avoid sun exposure and to protect their skin appropriately when they are outside. They should also be informed about the possible complications that can occur, especially if they apply sunscreen to irritated skin. The necessity of preventing damage by avoiding unprotected sun exposure is vitally important in tackling this disease. As this disease often affects younger people, they may need repeated advice to make sure they modify their behavior appropriately.
Besides preventive methods, patients need to understand the potential problems associated with treatment, especially when using a drug called thalidomide in young women. It’s important to realize that if a woman is taking thalidomide, she must also be using birth control to avoid the harmful effects the drug can have on an unborn baby.
