IF YOUR SKIN ITCHES IN THE SUN, READ THIS!

Actinic prurigo is an abnormal skin reaction which is characterized with intensely itchy skin on exposure to sunlight. It is otherwise called solar prurigo or solar dermatitis.

 

The exact cause of actinic prurigo is unknown. There is however strong genetic connection. That is, it can be inherited or passed on from parents to children. The exact cause is unknown but evidence suggests the disease process is driven by a delayed type-IV hypersensitive response to ultraviolet A and B (UVA and UVB) radiation in genetically predisposed individuals.

 

HOW DO YOU KNOW YOU HAVE ACTINIC PRURIGO?

The part of your body often exposed to sunlight get intensely itchy rash. This rash usually appears hours or days following sun exposure. In many patients, this condition persists throughout the year. The areas affected include:

  • Sun-exposed areas of the face such as the cheeks, nose, forehead, chin and earlobes. V of the neck and chest, upper sides of the arms and hands.
  • In about 60-70% of those having this condition, there is lips involvement. There is only lips involvement in about 10% of the cases.
  • In 45% of the cases, there is conjunctival (eyes) involvement. This is characterized by eye redness, brown pigmentation and photophobia.
  • After a prolong period of being with this condition, parts of the body covered with cloth can also get affected.

This condition starts from childhood into adulthood.

 

INVESTIGATIONS YOUR DOCTOR MIGHT REQUEST

Laboratory tests are done to rule out other diseases which are characterized with photosensitivity eg systemic lupus erythematosus. Examples of such investigations include are- Antinuclear antibody levels, anti-Rho and anti-La and porphyrin levels.

Your doctor might also request for histological study of the skin.

 

TREATMENT

There is no cure for actinic prurigo. The main goal is prevention by avoiding sun exposure. Patients must realise their condition will worsen during the sunniest months of the year and they must adhere to sun-protection strategies to avoid or reduce outbreaks.

Every effort should be made to practice rigorous sun-protection. Patient is to avoid sunlight especially from 10AM to 4PM, seek shade while outdoors, wear sunglasses, appropriate clothing, broad-brimmed hat, and avoid standing or working by the windows because of sunlight.

– In some cases, topical potent corticosteroids are helpful; their prolong use should be avoided. They can be substituted by tacrolimus 0.1% ointment, or pimecrolimus cream. These are useful for secondary eczematization.

– For possible bacteria infection, use topical antibiotics (fusidic acid, mupirocin), and if need be, oral antibiotics.

– Currently, the best treatment for actinic prurigo is thalidomide. The initial recommended dose is 100-200mg/day, depending on the severity of the disease. Usually, beneficial effects are noted within 50 days; however, lesions may recur upon discontinuation; therefore, it is best to taper the dose slowly. Many patients could control the disease with a dose of 25-50mg/week.

– Cyclosporine eyedrops are helpful for ocular involvement. In some cases, ophthalmologic surgery is needed.

CAUTION WITH THALIDOMIDE!

Although thalidomide is the best treatment known for this disease, there are various adverse effects that the patient should know and prevent. Thalidomide is teratogenic, so women of child-bearing age should use effective contraception methods, starting at 4 weeks before the initiation of the treatment and continuing until 4 weeks after ending it.

With thalidomide, peripheral neuropathy could occur, which usually begins with symmetrical painful paresthesias of the hands and feet with sensory loss in the lower extremities. The neuropathy can resolve slowly or may be irreversible.

Despite the adverse effects described, thalidomide is usually well tolerated, and peripheral neuropathy had been only rarely reported in most of the actinic prurigo treatment series.

For your information, actinic prurigo is sometimes called ‘Hutchinson prurigo.’

Disclaimer: Content here is solely for educational purpose. Speak with your doctor when needed.

 

REFERENCE

Dermatology advisor

Dermnetnz

www.ncbi.nlm.nih.gov/books/NBK499957/

MedScape