Essential fatty acid deficiency mimicking porphyria cutanea tarda in a patient with chronic cholestasis.

Essential fatty acid deficiency was documented in a 3-year-old boy with chronic cholestasis secondary to paucity of intrahepatic bile ducts (Alagille's syndrome). Dietary management had consisted almost exclusively of a proprietary formula with over 80% of the fat as medium-chain triglycerides. The bullous lesions involved mostly sun-exposed areas and were diagnosed initially as being compatible with acquired porphyria cutanea tarda. Improvement followed correction of the fatty acid abnormalities with a polyunsaturated fat supplement administered orally. We postulate that the association of fatty acid deficiency and abnormal vitamin E status contributed to skin damage, possibly involving photosensitizing compounds poorly cleared by the markedly cholestatic liver.