Kamal G. Ishak

A Histology Activity Index has been developed which generates a numerical score for liver biopsy specimens obtained from patients with asymptomatic chronic active hepatitis. Biopsies are graded in four categories: periportal necrosis, intralobular necrosis, portal inflammation, and fibrosis. Under code, three pathologists and three hepatologists evaluated 14 liver biopsy specimens obtained from five patients with asymptomatic chronic active hepatitis. Good correlation was seen between severity of liver biopsy lesions as judged by conventional histological descriptions and Histology Activity Index scores. Significant differences in Histology Activity Index score occurred in only 2 or 28 duplicate scorings of biopsy specimens by two observers. This system provides definitive endpoints for statistical analysis of serial changes in liver histology and offers an alternative to the use of conventional pathological descriptions in following the natural history and treatment responses of asymptomatic chronic active hepatitis.

We have evaluated the clinical and histopathological outcomes of patients who contracted chronic non A, non B hepatitis as a result of transfusions administered during heart surgery at the National Institutes of Health. Posttransfusion hepatitis developed in 65 of 1,070 (6.1%) patients and became chronic in 45 (69%) of those cases. Antibody to hepatitis C virus was detectable in 53 patients (82%) with posttransfusion non A, non B hepatitis. Thirty-three patients with chronic non A, non B hepatitis agreed to liver biopsy (group 1). In addition, six other patients with chronic posttransfusion non A, non B hepatitis were evaluated (group 2). These 39 patients were followed between 1 and 24 yr (mean = 9.7 yr). Cirrhosis developed in 8 patients (20%) between 1.5 and 16 yr after blood transfusion. Of the 33 patients in group 1, 11 (33%) died during follow-up. In two cases (6%), this was related to liver failure. At this writing, two additional patients (6%) have decompensated cirrhosis and one (3%) has debilitating fatigue. Twenty of 33 patients (61%) with histological evidence of chronic active hepatitis or cirrhosis are asymptomatic and have no clinical evidence of liver disease. Thus chronic non A, non B posttransfusion hepatitis appeared to be due to hepatitis C virus infection in most cases. It was associated with the development of cirrhosis in approximately 20% of cases and end-stage liver disease in 12% of patients followed prospectively. Most patients with histological evidence of cirrhosis or chronic active hepatitis, however, had minimal clinical evidence of liver disease within the time frame of this study. (Hepatology 1991;14:969-974.)

The clinical spectrum of isoniazid-induced liver injury seems to be clinically, biochemically, and histologically indistinguishable from viral hepatitis, except that the injury occurs primarily in persons older than 35 years. A possible relation between susceptibility of patients to isoniazid liver injury and rapid metabolism (acetylation) of the drug has been found. Examination of isoniazid metabolites showed that patients with rapid acetylator phenotype hydrolyze much more isoniazid to isonicotinic acid and the free hydrazine moiety than do slow acetylators. The hydrazine moiety liberated from isoniazid is primarily acetylhydrazine, and studies in animals show this metabolite to be converted to a potent acylating agent that produces liver necrosis. It seems likely that formation of chemically reactive metabolites is also the biochemical event initiating isoniazid liver injury in man. Recognition of the seriousness of isoniazid hepatic injury, not readily accepted at first, has led to revisions in the uses of isoniazid prophylaxis.