As a result of absorption of ultraviolet and visible light (peak sensitivity at 400 nm, with lesser peaks between 500-625 nm) by protoporphyrin in plasma and erythrocytes when blood circulates through the dermal vessels, free radicals are formed, erythrocytes become unstable and injury to the skin is induced.A significant increase in the hepatobiliary excretion of protoporphyrin can damage the liver through both cholestatic phenomena and oxidative stress - predisposing to hepatobiliary disease of varying degrees of severity

Diagnosis
EPP is generally suspected by the presence of acute photosensitivity of the skin and can be confirmed by detection of a plasmatic fluorescence peak at 634 nm. It is also useful to find increased levels of protoporphyrin in feces and the demonstration of an excess of free protoporphyrin in erythrocytes.Screening for FECH mutation on one allele or aminolevulinic acid synthase 2 gain-of-function mutation in selected family members may be useful, especially in genetic counseling. Liver biopsy confirms hepatic disease in EPP by the presence of protoporphyrin deposits in the hepatocytes that can be observed as a brown pigment within the biliary canaliculi and the portal macrophages. Macroscopically, the cirrhotic liver can have a black color due to protoporphyrin deposits. Using polarized light the characteristic Maltese cross shape of birefringent crystalline pigment deposits is found. The examination of liver tissue under a Wood’s lamp reveals a red fluorescence due to protoporphyrin. Liver biopsy is not helpful for estimation of prognosis of liver disease.
It seems to be effective in reducing circulating protoporphyrin levels.Bone marrow transplantation, liver transplantation, acetylcysteine, extracorporeal albumin dialysis, parenteral iron and transfusion of erythrocytes are alternative plans for treatment of EEP. Over-the-counter drug
Some over-the-counter drugs may help:

Proferrin is an oral heme supplement which may work similarly to Hematin. B. subtilis (a gram-positive soil probiotic) produces ferrochelatase, which may be able to convert some of the protoporphyrin in the intestine into heme. Beta carotene, though a recent meta analysis of carotene treatment has called its effectiveness into question. Epidemiology
Case reports suggest that EPP is prevalent globally. The prevalence has been estimated somewhere between 1 in 75,000 and 1 in 200,000 however it has been noted that the prevalence of EPP may be increasing due to a better understanding of the disease and improved diagnosis. An estimated 5,000–10,000 individuals worldwide have EPP. EPP is considered the most common form of porphyria in children. The prevalence in Sweden has been published as 1:180,000. History
Erythropoietic protoporphyria was first described in 1953 by Kosenow and Treibs and completed in 1960 by Magnus et al. at the St Johns Institute of Dermatology in London. See also
Xeroderma pigmentosum
Porphyria cutanea tarda
List of cutaneous conditions

References
External links
Erythropoietic protoporphyria at NLM Genetics Home Reference