Erythropoietic protoporphyria

Synonym(s)

Erythrohepatic protoporphyria; congenital erythropoietic protoporphyria; protopor-phyria

Definition

Inherited disorder of porphyrin-heme metabolism caused by mutations in the gene encoding ferrochelatase, resulting in accumulation of excess protoporphyrin that mediates a distinctive form of cutaneous photosensitivity

Pathogenesis

Mutations of the ferrochelatase gene, leading to excess protoporphyrin, a molecule capable of transformation to excited states by absorption of light energy; photoxida-tive damage to biomolecular targets in the skin, resulting in immediate phototoxic symptoms

Clinical manifestation

Immediate edema, erythema, and petechiae after sun exposure; occasional vesicles; chronic skin changes, including facial scars, perioral furrowing, and aged-appearing, thickened, or hyperkeratotic skin of the dorsal hands; with sustained, more intense, or frequent exposures, waxy scleroderma-like induration and/or weather-beaten or cobblestone textures of the face and dorsal aspects of hands; progressive liver failure in rare instances, with hepatosplenomegaly and jaundice

Differential diagnosis

Solar urticaria; acute tar photosensitivity; hereditary coproporphyria; porphyria cutanea tarda; pseudoporphyria; polymorphous light eruption; light-sensitive atopic dermatitis

Therapy

Beta-carotene 120-300 mg PO per day; sun avoidance*

References

Murphy GM (1999) The cutaneous porphyrias: a review. The British Photodermatology Group. British Journal of Dermatology 14o(4):573-581

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