Anogenital psoriasis: what causes it and how can it be treated?

Psoriasis is a very common skin condition that can cause a red scaly rash. It most often affects the scalp, causing dandruff, the outsides of the elbows and fronts of the knees.

We don’t fully understand the causes of the condition, although genetics are important as it often runs in families. The skin becomes inflamed and thickened, red and itchy. It’s not an infection, and can’t be passed from one person to another by contact. It is more common in smokers and people with HIV infection, and can be triggered by certain medications such as beta blockers. Stress is often a factor in flares of psoriasis.

It’s common to have psoriasis in the genital skin, and it’s seen in both males and females, adults and children. Psoriasis, like other skin conditions, can look different in genital skin and other body folds, which can make diagnosis more difficult.

The silvery scale that is seen in psoriasis elsewhere on the body and scalp is often lacking in body folds, but the typical well-defined edges and salmon-pink colour are usually present. Sometimes the skin of body folds can show secondary infection such as with candida (thrush), which can alter the appearances.

The rash of genital psoriasis is often a bright salmon-pink colour, sometimes with a silvery scale at the margins. It is symmetrical, and usually involves the skin between the buttocks as well as on the genitals, the mons and in the groin folds. The edges are well defined, sharply demarcated from the adjacent skin. It can sometimes crack painfully; this is called fissuring and is common near the anus.

There may be psoriasis elsewhere on the body, such as the scalp, knees and elbows. It can even go in the belly button and ears, and can cause changes in the nails. Sometimes it’s very itchy, but this is variable. It doesn’t affect the inside of the body.

Yes, psoriasis is not a contagious or sexually transmitted condition.

Psoriasis of the face, scalp and genital area is also called seborrhoeic dermatitis, so both are correct. It can also be called inverse psoriasis or flexural psoriasis.

Usually psoriasis is diagnosed on clinical information and by examining the skin all over; a well-defined red-pink dry rash in the typical body sites is diagnostic. If there is any doubt, a small skin biopsy can be taken for examination under the microscope. If infection is suspected, a swab or fungal scraping can the taken. It can be useful to test for other conditions that are associated with psoriasis such as high blood pressure, raised cholesterol and HIV infection.

There is currently no cure for psoriasis, but there are many effective treatments.

It’s important to avoid anything that makes it worse. Soap and shower gel, even organic, hypoallergenic and non-perfumed types, dry out the skin and can make psoriasis or any dry and itchy skin condition worse. It is helpful to wash with a bland moisturiser such as Cetraben or Diprobase cream. The moisturiser can be used several times daily to help keep the skin comfortable.

Yes. Mild steroid ointments can be applied once daily, sometimes in combination with anti-fungal or antibiotic treatments. Steroids can be very helpful but should not be used continuously for long periods as they can thin the skin, a particular consideration in genital sites as it can lead to stretch marks on the thighs.

• Non-steroid calcineurin inhibitor medications: are used in cream or ointment form as alternatives to steroids.  They do not cause skin thinning, but can sting or burn when first used.
• Vitamin D-based creams and ointments: are very useful in psoriasis, and can be used in addition to the steroid or calcineurin inhibitor treatments.
• Tar creams and lotions: are sometimes used, but these can irritate sensitive genital skin. Topical retinoids can be helpful too, again used with caution as they can irritate the skin.

There’s no doubt that treating skin conditions can be all of these things. However, at OneWelbeck we will do our best to ensure that your treatment plan is manageable for your lifestyle.

There are tablets and injection treatments for psoriasis which may be suitable for you, however these types of treatment can have more side effects than creams, as well as needing more monitoring with blood tests. These treatments are used for people with more severe psoriasis, and for psoriasis that is having a significant impact on a person’s health or wellbeing.

We do use phototherapy (UV treatment) for psoriasis, however it’s not suitable for genital psoriasis.

The British Association of Dermatologists and DermNetNZ  both have reliable up-to-date information on psoriasis and its treatments.

Your doctor at OneWelbeck can help to answer specific questions and find the best approach for your skin condition, taking into account your preferences and other relevant factors such as your general health and lifestyle.