The pathology of the liver in porphyria cutanea tarda.

We report the findings in 53 biopsies from 45 patients with porphyria cutanea tarda (PCT). Red autofluorescence and birefringent acicular cytoplasmic inclusions were constant findings in all untreated cases. Autofluorescence occurs in other hepatic porphyrias, but acicular inclusions appear to be specific for PCT; we have seen them in subclinical porphyria and before development of cutaneous symptoms. They are probably uroporphyrins and they trend to disappear during rinsing by water during most staining procedures. We recommend unstained paraffin sections for their demonstration. Liver damage in PCT has features distinct from other liver diseases, including alcoholic liver disease. These include constant but mild periportal siderosis, focal lipofuscin deposition, focal lobular hepatocyte necrosis associated with groups of pigment-laden macrophages, focal steatosis, marked hepatocyte hyperplasia and the presence of periductal lymphocyte aggregates. The latter have not been previously described in PCT and were present in 43% of our cases. There is a direct relationship between increasing age and progressive distortion of liver architecture, with fibrosis present at a mean age of 48 years, cirrhosis at 57 and hepatocellular carcinoma at 66. The characteristic liver histology and the natural history of PCT are against this being the result of any non-specific liver damage and favour instead a specific liver disease whose pathogenesis may be mainly the result of the metabolic defect of PCT.