Porphyria Cutanea Tarda
PCT is the most common form of porphyria, and is known to cause skin lesions and rashes, and sunlight sensitivity.
Symptoms of PCT can vary, and liver abnormalities may develop.
Phlebotomy is a treatment for PCT, and affected individuals are advised to avoid direct sunlight.
The skin features of PCT, HCP and VP are identical. They are caused by excess porphyrin accumulating in the skin (dermis). These porphyrins react to light (visible violet light), which leads to skin damage. This can result in a number of issues including the skin becoming fragile, with easy tearing from minor trauma. PCT, HCP and VP are known as bullous porphyrias, as they all can lead to skin blistering. Fluid, or blood-filled blisters of varying sizes (usually 0.5-1cm) can be seen in sun-exposed sites, particularly the backs of the hands, and to a lesser extent the face, tops of the feet and scalp. (See Figure 1.) These can be slow to heal, leaving sores and scabs which heal leaving marks and scars. Small (~1mm), firm, white lumps known as milia form as blisters heal. These resolve slowly over months to years. (See Figures 1 & 2.) The blisters can be uncomfortable or sore, especially when they are very tense/distended, or when there are open areas. Affected areas can also be itchy as they heal.
Increased pigmentation can sometimes be seen in affected areas, particularly in those with darker skin types. (See Figure 3.) Rarely, other skin problems can occur, including hardening of the skin (sclerodermoid change) usually of the chest, excess hair growth (hirsutism or hypertrichosis) especially on cheeks, or scarring hair loss (usually where there have been blisters) and nail changes (nail lifting - onycholysis). (See Figure 1).
The skin changes are usually the first sign of PCT, and are readily recognised and diagnosed by dermatologists.
The skin changes will usually resolve with time and treatment of the porphyria.
When PCT is treated, the fragility and blistering stops over months, and the remaining changes including milia, pigmentation and hirsutism may take 1-2 years to return to normal.
Strict sun protection is an important part of keeping the skin in good condition. This should be all year round, not just in summer. Sun protection should include wearing long sleeved clothing of a dense enough fabric that when held up to the light, no light comes through. A broad brimmed hat, sunglasses and closed shoes should be worn whenever outdoors. Sunscreen is important, but not as effective as clothing, as visible light can penetrate most sunscreens and reach the porphyrins in the upper part of the skin. Sunscreen should be high in zinc, and ideally opaque (rather than invisible). A tint can help to make the sunscreen more cosmetically appealing, and block more light from penetrating. Car windows should be tinted to the darkest legal tint. Driving gloves are recommended for long car trips. Also consider gloves for gardening, sport and manual labour, to minimise both light exposure and injuries.
Treatment of blisters includes puncturing them with a sterile needle to release the fluid, which will result in improved comfort and more rapid healing. A dressing can be used to protect the affected areas while they heal and help to prevent infection. Regular bland moisturiser or hand cream should be applied. Milia can be extracted by pricking the overlying skin and squeezing it out.
A typical blister on back of hand. When these break, they become an erosion. There is an erosion on the left index finger, some old scars (4th finger) and milia at the base of the 4th finger. Note the nails that have lifted up off the nail bed causing a white appearance (onycholysis).
Erosions and milia (see left 2nd finger).
Further treatment of PCT
Treatment of PCT involves treating the underlying causes of liver damage eg avoidance of alcohol, treatment of Hepatitis B or C. Iron overload is the underlying reason that the porphyrins accumulate. This is treated by venesection, removing blood. This leads to new red blood cell formation, which uses up the excess iron. This is performed at centres such as the Red Cross, some Pathology Collection services, or hospitals. In those people where venesection is not ideal (eg the elderly, anaemia), sometimes a medication called hydroxychloroquine is prescribed. This allows the porphyrins to be excreted better, however as it does not use up the excess iron, it is not as effective as venesection.