Convertibility and Correlation with Laboratory Changes in Chronic Hepatitis C

Ishak (modified Knodell score) and METAVIR scores are the most widely accepted scoring systems for assessment of fibrosis and necroinflammation in dealing with chronic hepatitis C. In METAVIR, only interface hepatitis and lobular necrosis determine the grade of activity, while in Ishak, portal infiltrate and confluent necrosis are included with the two previous parameters. Confluent necrosis is very rare in chronic hepatitis C, that in most patients the actual score limit is 12 instead of 18 (Ishak score), that mostly underscore the actual necroinflammation. Also, portal inflammatory infiltrate may reflect immunological response rather than necroinflammation. This may explain the discrepancy between enzyme elevation and necroinflammatory score as determined by Ishak score (modified HAI) in assessment of chronic hepatitis C biopsy specimens. On the other hand, no study has clearly tested such discrepancy in applying METAVIR. Some of the terminologies applied in METAVIR are in need of revision or declaration. For example; the term “septa” is used to mean actual fibrous bridges, while in Ishak score both terms; septa and bridges; are applied by different meaning. Ishak et al, 1995, in their system, applied both terminologies (septa & bridges), however in completely different meaning. Septa, means expansion of portal tract edges without formation of bridges or actual connection between portal areas or portal area and central vein (1). On the other hand, the term bridge was applied to actual fibrous connection between two portal areas or portal area and central vein. Because of this confusion, some studies comparing both scoring systems have committed some mistakes. Some studies have compared both Ishak and METAVIR systems, but they included small number of patients or included hepatitis B and hepatitis C. Therefore, the objectives of this chapter are:  Revision of histological grading and staging in chronic hepatitis C.  Clarification of the METAVIR terminology for future applications.  Establishing an Ishak to METAVIR fibrosis score conversion table.