Disseminated superficial actinic porokeratosis

Disseminated superficial actinic porokeratosis

What is disseminated superficial actinic porokeratosis?

DSAP is a skin condition with multiple, dry, scaly rings, each measuring up to 1 cm (1/2 inch) across. They are found mainly on the forearms and legs, in sun-exposed sites. It is sometimes confused with actinic keratosis which is also caused by sun exposure (See Patient Information Leaflet on Actinic Keratoses); however, actinic keratosis is more likely to arise on the face and hands.

DSAP is twice as likely to develop in women compared with men and is more common in lighter skin type. It normally develops between 30-50 years of age. It is not contagious.

There are multiple other types of porokeratosis, which affect different age groups or present in slightly different ways.

Keep up to date with the latest research about disseminated superficial actinic porokeratosis and all things skin related with our newsletter.

More on this conditionintroduction

What does it look like?

View larger

Main body location

Arm, Leg


Can it appear anywhere?



What causes disseminated superficial actinic porokeratosis?

DSAP is thought to be caused by a variety of factors. There is a genetic predisposition, but ultraviolet light exposure is thought to be the main cause. This condition tends to affect sun-exposed areas on people with fair skin who burn easily and tan poorly in the sun. It may appear more obvious in summer and less obvious in winter. Lastly, individuals taking medications or with illnesses that weaken the body’s immune system are also more likely to develop this skin condition.

Is disseminated superficial actinic porokeratosis hereditary?

It may be in some individuals. There are multiple genes on different chromosomes which have been associated with DSAP. This can occur in families in an autosomal dominant pattern, this means on average about half of the children of an affected parent could develop DSAP, although a certain amount of accumulated sun exposure is required for it to appear. The genetic mutation may also arise newly without any family history (sporadic).

What are the symptoms of disseminated superficial actinic porokeratosis?

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

What does disseminated superficial actinic porokeratosis look like?

DSAP normally starts as a brownish red or brown spot and can grow from 2 mm up to 1 cm (1/2 inch) in diameter. The affected area normally has a thinned centre surrounded by a 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 squamous cell carcinomas (SCCs) at the affected site, see Patient Information Leaflet on SCC. 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 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.

How is disseminated superficial actinic porokeratosis diagnosed?

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, may be sufficient to enable a doctor to make the diagnosis.

Can disseminated superficial actinic porokeratosis be cured?

Unfortunately, there is no cure for DSAP. The best way to avoid worsening of this skin condition is to avoid exposure to the sun and regular use of sunblock.

How can disseminated superficial actinic porokeratosis be treated?

There is no effective treatment for DSAP and some of the treatments that are offered may have significant side effects or may not be available on the NHS. Many do not make a difference to the long term outcome of the disease. For the majority of individuals, no treatment is required apart from sun avoidance and monitoring of lesions in case they become cancerous.

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

Self care (What can I do?)

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

Top sun safety tips

  • Protect your skin with adequate clothing, wear a hat that protects your face, neck and ears, and a pair of UV protective sunglasses. Choose sun protective clothing (with permanently sun-protective fabric, widely available for adults and children) if you have fair skin or many moles.
  • Spend time in the shade between 11am and 3pm when it’s sunny. Step out of the sun before your skin has a chance to redden or burn.
  • When choosing a sunscreen look for a high protection SPF (current recommendations are SPF 30 or 50+) to protect against UVB, and the UVA circle logo and/or 4 or 5 UVA stars to protect against UVA. Apply plenty of sunscreen 15 to 30 minutes before going out in the sun, and reapply every two hours and straight after swimming and towel-drying.
  • Keep babies and young children out of direct sunlight.
  • UVA can penetrate through glass and be present on cloudy days, therefore it is important to wear sunscreen in these circumstances too.
  • The British Association of Dermatologists recommends that you tell your doctor about any changes to a mole or patch of skin. If your GP is concerned about your skin you are advised to see a Consultant Dermatologist – an expert in diagnosing skin cancer. Your doctor can refer you for free through the NHS.
  • Sunscreens are not an alternative to clothing and shade, rather they offer additional protection. No sunscreen will provide 100% protection.

Vitamin D advice

  • The evidence relating to the health effects of serum Vitamin D levels, sunlight exposure and Vitamin D intake remains inconclusive. Avoiding all sunlight exposure if you suffer from light sensitivity, or to reduce the risk of melanoma and other skin cancers, may be associated with Vitamin D deficiency.
  • Individuals avoiding all sun exposure should consider having their serum Vitamin D measured. If levels are reduced or deficient they may wish to consider taking supplementary vitamin D3, 10-25 micrograms per day, and increasing their intake of foods high in Vitamin D such as oily fish, eggs, meat, fortified margarines and cereals. Vitamin D3 supplements are widely available from health food shops.
This information is provided by the British Association of Dermatologists.

Keep up to date with the latest research and all things skin related with our newsletter.

Sign up for the latest research

Discover more news and information about bowen’s disease

Enter your details below to get updates about this condition that may help you or read more on our website if you need further information right now.


Before you go…sign up for the latest research

Discover more news and information about our research bowen’s disease

Enter your details below to get updates about this condition that may help you or read more on our website if you need further information right now.

Sensitive images

This directory contains sensitive content of skin conditions

This icon will show when the sensitive content is present.