Erythropoietic protoporphyria
| Erythropoietic protoporphyria | |
|---|---|
 |
|
| Chronic skin lesions of EPP | |
| Classification and external resources | |
| Specialty | endocrinology, dermatology |
| ICD-10 | E80.0 (ILDS E80.010) |
| ICD-9-CM | 277.1 |
| OMIM | 177000 |
| DiseasesDB | 4484 |
| eMedicine | derm/473 |
| MeSH | C06.552.830.812 |
| Orphanet | 79278 |
Erythropoietic protoporphyria (EPP) is a form of porphyria, which varies in severity and can be very painful. It arises from a deficiency in the enzyme ferrochelatase, leading to abnormally high levels of protoporphyrin in the erythrocytes, plasma, skin and liver. The severity varies significantly from individual to individual.
A clinically similar form of porphyria, known as X-Linked dominant protoporphyria, was identified in 2008.
EPP usually presents in childhood with the commonest mode of presentation as acute photosensitivity of the skin. It affects areas exposed to the sun and tends to be intractable. A few minutes of exposure to the sun induces pruritus, erythema, swelling and pain. Longer periods of exposure may induce second degree burns. After repetitive exposure, patients may present with lichenification, hypopigmentation, hyperpigmentation and scarring of the skin.
EPP usually first presents in childhood, and most often affects the face and the upper surfaces of the arms, hands, and feet and the exposed surfaces of the legs. Most patients, if the EPP is not as severe, manifest symptoms with onset of puberty when the male and female hormone levels elevate during sexual development and maintenance. More severe EPP can manifest in infancy. EPP can be triggered through exposure to sun even though the patient is behind glass. Even the UV emissions from arc welding with the use of full protective mask have been known to trigger EPP. EPP can also manifest between the ages of 3 and 6.
Prolonged exposure to the sun can lead to edema of the hands, face, and feet, rarely with blistering and petechiae. Skin thickening can sometimes occur over time.
People with EPP are also at increased risk to develop gallstones. One study has noted that EPP patients suffer from vitamin D deficiency.
Protoporphyrin accumulates to toxic levels in the liver in 5-20% of EPP patients, leading to liver failure. The spectrum of hepatobiliary disease associated with EPP is wide. It includes cholelithiasis, mild parenchymal liver disease, progressive hepatocellular disease and end-stage liver disease.
A lack of diagnostic markers for liver failure makes it difficult to predict which patients may experience liver failure, and the mechanism of liver failure is poorly understood. A retrospective European study identified 31 EPP patients receiving a liver transplant between 1983 and 2008, with phototoxic reactions in 25% of patients who were unprotected by surgical light filters. The same study noted a 69% recurrence of the disease in the grafted organ. Five UK liver transplants for EPP have been identified between 1987 and 2009.
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