Liver tissue from five children with cystic fibrosis, obtained through percutaneous liver biopsies, have been investigated via light and electron microscopy. None of the patients had clinical evidence of liver disorder, and their blood chemistry was mainly normal.

Light microscopy showed slight fibrosis in three cases, more advanced fibrosis in one case and focal cirrhotic changes in one case. All patients had fatty infiltration in the hepatocytes and glycogen in the nuclei of these cells.

Electron microscopy showed an increase in the number of Ito cells around the portal tracts and also fibrosis in all patients. In the majority of hepatocytes, no evident necrosis was seen. Hypertrophy of the smooth endoplasmic reticulum and the Golgi apparatus were noted. Large lysosomes containing lipofuscin and lipids were also present. No direct evidence of cholestasis could be seen in the hepatocytes. The bile canaliculi were not dilated and did not contain bile plugs. No bile pigment was seen in the cells, and direct evidence of cholestasis was thus not found in the hepatocytes. Other organelles, such as the rough endoplasmic reticulum, peroxisomes and mitochondria, had a normal appearance. Bile ducts, even when seen in fibrotic portal tracts, were not dilated.

The ultrastructural findings cannot explain the basis for the liver cell damage. Cholestasis does not seem to be a presumable etiological factor as judged from the findings in the present study.