EPP is a cutaneous porphyria that results in lifelong sunlight sensitivity.
It often presents first in childhood.
There is no cure for EPP, but it can be managed by limiting exposure to sunlight and other dermatological treatment.
The skin changes of EPP are distinct from the other porphyrias. This is because the porphyrin accumulates in the blood vessels in the skin, rather than the dermis like in the bullous (blistering) porphyrias. The main manifestation is skin pain on exposure to light (visible violet light). This can occur on cloudy days, and in winter, on any areas exposed to the light. Pain can start after anything from seconds to hours, depending on the individual.
There may be some initial ‘warning’ symptoms such as tingling, burning or itch. This is known as a ‘prodrome’. If the affected person removes themselves from the light at this stage, the symptoms are usually rapidly reversible. However, if they remain exposed to the light, the symptoms progress to intense pain which can last hours to days. The pain is not able to be relieved by standard pain relief medication such as paracetamol or ibuprofen, and patients report the only useful thing is immersing the affected areas in cold water or using a fan/air-conditioning. There may not be any visible signs during the episode of pain, but sometimes mild redness and swelling can be seen, or in severe instances, purple discoloration. (See Figure 4.) The lack of clear changes during episodes of pain often makes diagnosis of EPP challenging.
Over the years, repeated episodes will result in skin changes of thickened skin over the backs of the hands and scarring and furrows around the mouth, on the nose and over the knuckles. (See Figure 5.)
Reddish/purple discolouration and swelling of the toes and tops of the feet when thongs were worn.
Thickening of skin over the knuckles and scarring on thumb and fingers.
Avoidance of light, and strict sun/light protection are the most important measures in preventing pain in EPP. These measures are the same as described for the bullous porphyrias, with a strong focus on clothing. A UPF rating of 50+ is helpful for identifying clothing that block light, and are readily available in stores that sell outdoor clothing (eg camping/hiking/fishing/sporting stores). Opaque sunscreen should be used every day and reapplied frequently. Fake tan (self-applied creams or sprays) can also help prevent light penetrating the skin. In EPP, caution should also be taken with other sources of light including indoors - strong fluorescent lights and incandescent bulbs can cause issues, as can bright screens. Dimmers, shades and filters should be used, as well as increased distance from the light source.
Further treatment of EPP
Apart from light protection, there are a few other options for treatment for patients with EPP.
Phototherapy, also known as light treatment or narrow band UVB treatment, is a form of treatment with delivers a specific wavelength of light to the skin (311nm). This is not the wavelength that causes EPP, and not the same as a tanning bed. It has the effect of activating the pigment cells to produce melanin (developing a tan). The increased pigment in the skin can help to block visible light penetration. It also thickens the skin, which can also hinder light from penetrating as far as where the blood vessels are. There is additionally an anti-inflammatory effect.
Light treatment is administered by dermatologists, usually 3 times a week for around 6-8 weeks, starting with a very small amount, gradually increasing over time. It is usually done in Spring, to allow better sun tolerance over Summer. It is repeated annually. The main potential side effect is sunburn.
Beta-carotene is a red-orange pigment found in vegetables such as carrots. It is converted into Vitamin A in the body. In high quantities/as supplements, it causes a yellow/orange discolouration of the skin, and has potential anti-oxidant benefits. It has not been proven to reduce the symptoms of EPP.
Afamelanotide is a form of melanocyte stimulating hormone. This activates melanocytes to produce pigment, which reduces light penetration and subsequent damage. It is administered as an implant into the fat layer under the skin of the stomach above the hip bone, under local anaesthetic. This is replaced every 2 months.
It is currently available in some parts of the world including the UK, Europe and is FDA approved in the USA. Whilst it is TGA approved for use in Australia, it is not yet on the Pharmaceutical Benefits Scheme (PBS), and it’s cost makes it prohibitive for most people.