Cytoplasmic inclusion bodies and minimal hepatitis: fibrinogen storage without hypofibrinogenemia.

A 12-year-old Japanese boy had chronic elevation and fluctuation of serum transaminase levels since infancy, with no signs or symptoms of liver failure. Usual infections or metabolic disorders were eliminated from consideration. No coagulopathy or abnormality in plasma concentrations of clotting factors was found. Light microscopy of liver biopsy specimens obtained at ages 2, 5, and 7 years showed slight hepatocyte disarray and minimal mononuclear-leukocyte lobular inflammation, with eosinophilic inclusion bodies in the cytoplasm of hepatocytes throughout the lobule. These bodies stained with the periodic acid-Schiff (PAS) technique; the PAS-positive material was partly diastase digestible and on immunostaining marked for fibrinogen but not for alpha 1-antitrypsin. On transmission electron microscopy, the bodies were represented by finely granular material contained within membranes and were interpreted as tentatively endoplasmic reticulum. Fibrinogen storage may be manifest as minimal hepatitis without coagulopathy.