Disseminated superficial actinic porokeratosis

DSAP is thought to be caused by different factors. Genes may play a role, but ultraviolet light exposure is thought to be the main cause. This condition tends to affect sun-exposed areas on people with white skin who burn easily and tan poorly in the sun. It may appear more obvious in summer and less obvious in winter. Individual with weakened immune system, due to illness or medications are also more likely to develop this skin condition.

Is disseminated superficial actinic porokeratosis hereditary?

In some cases, DSAP may run in families. If a parent has DSAP, there is a chance their children could develop it too. However, long-term sun exposure may also play a role, and sometimes DSAP can arise even without a family history.

Top sun safety tips

The most important precaution to take is to protect your skin from sun damage:

Routine sun protection is rarely necessary in the UK for people of colour, particularly those with black or dark brown skin tones. However, there are important exceptions to this; for example, sun protection is important if you have a skin condition, such as photosensitivity, vitiligo or lupus, or if you have a high risk of skin cancer, especially if you are taking immunosuppressive treatments (including organ transplant recipients) or if you are genetically pre-disposed to skin cancer. Outside of the UK in places with more extreme climates, you may need to follow our standard sun protection advice.

Vitamin D advice

People who avoid sun exposure may be at risk of vitamin D deficiency. They should have their vitamin D levels checked. If the levels are low, they may consider:

• Vitamin D supplements (dosing advice can be obtained from the GP)
• Increasing intake of food rich in vitamin D such as oily fish, eggs, meat and cereal.

DSAP is usually without symptoms. The affected areas often feel dry and rough to touch. However, sun exposure can cause them to itch or sting and grow in size  and number.

DSAP normally starts as a brownish-red or brown spot and can grow from 2 mm up to 1 cm  in diameter. The affected area normally has a thinned centre surrounded by a pink or red ridge-like border.

Is disseminated superficial actinic porokeratosis cancerous?

DSAP is generally harmless but, in very rare cases, individuals may be at risk of developing a type of skin cancer called squamous cell carcinoma (SCC) at the affected site This tends to present as an enlarging raised lump within the original DSAP, which may be painful. Therefore, it is important to monitor the area and let your GP  or dermatologist know if there is any change. The risk is higher for rarer subtypes like linear porokeratosis or giant porokeratosis.

Many people with DSAP have also had significant exposure to the sun and so may also have other skin lesions caused by sun damage including skin cancer.

Image DermNetNZ.

Sometimes a sample of the affected area may be removed under local anaesthetic by a dermatologist for microscopic examination in the laboratory (known as a skin biopsy). However, the appearance of the affected area, along with the history, is usually  sufficient to enable a doctor to make the diagnosis.

Can disseminated superficial actinic porokeratosis be cured?

There is no cure for DSAP. The best way to avoid the worsening of this skin condition is to avoid sun exposure , use sunblock regularly and monitor the lesions for changes.

How can disseminated superficial actinic porokeratosis be treated?

There is no effective treatment for DSAP to date and some of the available treatments may have significant side effects or may not be available on the NHS. Many treatments do not make a difference to the long-term outcome of the condition. For most individuals, no treatment is  necessary.

However, if the rash is itchy or if the appearance is troublesome, methods which have been tried in the past include the following: