This scheme represents an extension of the original Knodell system, with a number of minor modifications. Firstly, a continuous scale is used for scoring each of the features assessed. Secondly, necroinflammatory activity and fibrosis are considered as separate categories. Thirdly, confluent necrosis is separated from periportal hepatitis and is included as a separate category of necroinflammatory activity. The term interface hepatitis was used in place of ‘‘piecemeal necrosis,’’ to reflect the growing evidence that apoptosis, not necrosis, occurs at the limiting plate.