This is an overview of the cutaneous
porphyrias. It is a narrative review based on the published literature and my personal experience; it is not based on a formal systematic search of the literature. The cutaneous
porphyrias are a diverse group of conditions due to inherited or acquired
enzyme defects in the
porphyrin-
haem biosynthetic pathway. All the cutaneous
porphyrias can have (either as a consequence of the
porphyria or as part of the cause of the
porphyria) involvement of other organs as well as the skin. The single commonest cutaneous
porphyria in most parts of the world is acquired
porphyria cutanea tarda, which is usually due to chronic
liver disease and liver
iron overload. The next most common cutaneous
porphyria, erythropoietic protoporphyria, is an inherited disorder in which the accumulation of bile-excreted
protoporphyrin can cause
gallstones and, rarely,
liver disease. Some of the
porphyrias that cause blistering (usually
bullae) and fragility (clinically and histologically identical to
porphyria cutanea tarda) can also be associated with acute neurovisceral
porphyria attacks, particularly
variegate porphyria and
hereditary coproporphyria. Management of
porphyria cutanea tarda mainly consists of visible-light photoprotection measures while awaiting the effects of treating the underlying
liver disease (if possible) and treatments to reduce serum
iron and
porphyrin levels. In
erythropoietic protoporphyria, the underlying cause can be resolved only with a bone marrow transplant (which is rarely justifiable in this condition), so management consists particularly of visible-light photoprotection and, in some countries, narrowband ultraviolet B
phototherapy.
Afamelanotide is a promising and newly available treatment for
erythropoietic protoporphyria and has been approved in Europe since 2014.