Porphyria cutanea tarda (PCT), the condition resulting from a deficiency of hepatic uroporphyrinogen decarboxylase activity, is the commonest form of porphyria. Both acquired and familial form exist and are commonly associated in adults with liver disease and hepatic iron overload. The condition is extremely rare in children; most cases of childhood PCT are familial and some particularly severe cases have been shown to have a hepatoerythropoietic porphyria or homozygous uroporphyrinogen decarboxylase deficiency. A case is described of hepatoerythropoietic porphyria in which the disease was first precipitated at the age of two by a coincidental hepatitis A infection and improved as the hepatitis cleared. This paper reviews the evidence that viral hepatitis may precipitate overt PCT in children in a manner analagous to the precipitation of PCT in adults by alcohol associated liver disease. (Gut 1993; 34: 1632-1634 PCT is rarely manifest in infancy or childhood, and with the exception of an outbreak in Turkey, where large numbers of children developed PCT after ingesting wheat contaminated with hexachlorobenzene,2 few cases of infantile PCT have been described.1'7 A subgroup of affected children have a form of PCT characterised by severe photosensitivity starting in early childhood, considerably raised porphyrins, and a characteristic raised erythrocyte protoporphyrin. '22 These changes are often severe enough to mimic congenital erythropoietic porphyria. This condition has been shown to represent the homozygous form of familial PCT, with uroporphyrinogen decarboxylase activities typically being less than 10% of the control range,23 and has been labelled hepatoerythropoietic porphyria. The underlying genetic defect has now been determined in some patients.2"25 Both homozygous and compound heterozygous mutations have been identified.We describe here a two year old child in whom severe PCT was apparently precipitated by hepatitis A. Biochemical characterisation of the enzyme defect suggests the presence of hepatoerythropoietic porphyria, the severity ofthe PCT declined as the hepatitis improved.Case report A two year old black child presented to a paediatric hospital. The child had passed red urine and had developed a skin eruption over the preceding month. Both parents were healthy, and the child had had no previous medical or dermatological problems. There was no history of exposure to medicines, chemicals, or pesticides. The parents were not consanguineous.The child was well nourished; height and weight fell on the 50th percentile. Hypo and hyperpigmented patches on the nose and cheeks were noted. Erosions, scabs, and pigmentary changes were noted on her hands, cheeks, and forehead. Her hands and fingers were foreshortened. The nails showed onycholysis. She was mildly jaundiced. Her liver was slightly enlarged but not tender. No splenomomegaly was noted and there were no signs of hepatic decompensation.Serum chemistry suggested hepatitis (Table I).A full blood count was normal. IgM antibodies to hepatitis ...
