Cutaneous aspects of the porphyrias.

The clinical features of the porphyrias are often characteristic; and all can be definitively diagnosed by appropriate biochemical tests. Many of the cutaneous lesions are thought to be the result of photochemical damage which occurs due to 400 nm radiation exciting abnormally high concentrations of porphyrins in the skin. Others are probably based on hormonal or unidentified systemic factors. The effects of exogenous environmental porphyrinogenic agents have become increasingly well understood in recent years and at present treatment for many of the porphyrias is available. Early diagnosis, aided by recognition of the initial cutaneous signs and symptoms, is crucial for rapid implementation of appropriate therapy.