| Category | Criteria | Score |
| Mixed portal inflammatory infiltrate | Mostly lymphocytic inflammation involving, but not noticeably expanding, a minority of the triads | 1 |
| Expansion of most of all of the triads, by a mixed infiltrate containing lymphocytes with occasional blasts, neutrophils and eosinophils | 2 |
| Marked expansion of most or all of the triads by a mixed infiltrate containing numerous blasts and eosinophils with inflammatory spillover into the periportal parenchyma | 3 |
| Bile duct epithelial inflammation and damage | A minority of the ducts are cuffed and infiltrated by inflammatory cells and show only mild reactive changes such as increased nuclear:cytoplasmic ratio of the epithelial cells | 1 |
| Most or all of the ducts infiltrated by inflammatory cells. More than an occasional duct shows degenerative changes such as nuclear pleomorphism, disordered polarity and cytoplasmic vacuolization of the epithelium. | 2 |
| As above for 2, with most or all of the ducts showing degenerative changes or focal lumenal disruption | 3 |
| Venous endothelial inflammation | Subendothelial lymphocytic infiltration involving some, but not a majority of the portal and/or hepatic venules | 1
|
| Subendothelial infiltration involving most or all of the portal and/or hepatic venules with or without confluent hepatocyte necrosis/dropout involving a minority of perivenular regions | 2 |
| As above for 2, with moderate or severe perivenular inflammation that extends into the perivenular parenchyma and is associated with perivenular hepatocyte necrosis | 3 |
