[Porphyria in dermatology].

Porphyrins are fluorescent chemicals excited by visual light. Skin changes in patients with porphyrias develop when the skin is exposed to sunlight and porphyrins have precipitated. This reaction is phototoxic. Since the phototoxic reaction varies with each porphyria, each porphyria demonstrates different skin changes. Conversely, skin changes do not develop if skins are completely protected from exposure to the sun in patients with porphyrias with show severe abnormalities in the metabolism of porphyrin pathways. In Japan, relatively popular porphyrias in dermatology clinic are porphyria cutanea tarda (PCT), erythropoietic protoporphyria (EPP) and congenital erythropoietic porphyria (CEP). Histopathologically, one of the most important findings in porphyria is a deposition of PAS positive materials at the dermo-epidermal junction and around the small blood vessels in the dermis.