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In contrast to all other vascularized organ allografts, chronic rejection (CR) of the liver is potentially reversible. We therefore studied demographic, perioperative, biochemical, and histologic features associated with reversibility or progression to graft failure. Using very stringent clinical and histological criteria, we identified a subgroup of 23 of 916 patients receiving primary liver allografts with CR from the Liver Transplantation Database. Of these, 13 experienced graft failure as a result of CR, and 10 patients recovered to normal histology or liver injury test results. Male-to-female sex mismatch (p = 0.07), younger recipient age (p = 0.09), younger donor age (p = 0.06), white-to-white race match (p = 0.09), primary diagnosis of biliary atresia (p = 0.02), and cold ischemia time of more than 12 hours (p = 0.02) were associated with graft failure. Patients who eventually recovered from CR were more likely to have acute rejection within the first 2 weeks (70% vs 23%; p = 0.04), had a higher number of acute rejection episodes (p = 0.08), and were more likely to have been treated with OKT3 (90% vs 46%, p = 0.07). Although overlap existed in the histopathologic findings between the patients whose grafts failed and those who recovered, those patients who developed bile duct loss in more than 50% of the portal tracts (p < 0.01), severe (bridging) perivenular fibrosis (p = 0.05), and the presence of foam cell clusters (p = 0.06) were more likely to require retransplantation. In contrast to other solid organ allografts, CR of the liver is not an irreversible process. These findings can be used to understand the evolution of CR and to design a biologically correct and clinically relevant staging system.

A study was conducted to assess the inter and intrarater agreement for the histopathologic features and diagnosis of chronic rejection (CR) and several other important causes of late liver allograft dysfunction. On two occasions, five pathologists, experienced with liver transplantation, reviewed a set of 49 slides representing a range of diagnoses, without knowledge of the clinical history or liver injury test results. The readings were correlated with the original histopathologic diagnosis, liver injury tests, and clinicopathologic follow-up. Assessment of biopsy adequacy (kappa = 0.69) and portal tract counts (kappa = 0.79) showed good to excellent intrarater agreement, whereas interrater agreement for these variables was moderate to good, respectively (kappa = 0.44 and 0.65). Likewise, the intrarater agreement for the diagnosis of CR (kappa = 0.68), hepatitis (kappa = 0.77), and obstructive cholangiopathy (kappa = 0.55) showed good to excellent agreement, whereas the interrater agreement for these same diagnoses ranged from fair to good (kappa = 0.58, 0.46, and 0.25, respectively). In 18 specimens, there was a near unanimous diagnosis of CR across both readings. These biopsies were obtained at a median of 7.1 months (range, 42 days to 4.9 years) after transplantation, and the average number of portal tracts was 8.4 (range, 4-15). Interestingly, only 13 of these 18 specimens showed bile duct loss in >50% of the portal triads; the remaining cases showed atrophy/pyknosis of the biliary epithelium in a majority of small bile ducts. Clinicopathologic correlation showed that these 18 biopsies were obtained from 16 grafts from 15 patients, 14 of whom ultimately required retransplantation or died of or with CR, whereas two of the grafts/patients recovered. A high rate of sensitivity (92%) and a somewhat lower, but acceptable, rate of specificity (71% to 80%) was found for the diagnosis of CR. Chronic rejection and other causes of late liver allograft dysfunction can be diagnosed reliably by a group of pathologists experienced with liver transplantation, and the diagnosis of CR correlates with clinical course and liver function abnormalities. Expanded criteria for the diagnosis of CR are presented, and potential problem areas for practicing pathologists are discussed.

Albumin is a ubiquitous protein synthesized only by hepatocytes. Detection of albumin messenger RNA (mRNA) in neoplastic and non-neoplastic tissues using in situ hybridization may be useful in demonstrating hepatocellular differentiation. We investigated the presence of albumin mRNA by in situ hybridization in 69 hepatic and 29 extrahepatic tumors to determine its sensitivity and specificity for hepatocellular differentiation. Albumin mRNA was detected in 22 of 23 hepatocellular carcinomas (96%); all hepatoblastomas, hepatocellular adenomas, and focal nodular hyperplasias; and within the hepatoid areas of an extrahepatic malignant mixed germ cell tumor. All other hepatic and extrahepatic tumors were negative for albumin mRNA. The staining was intense in focal nodular hyperplasias, weak in hepatocellular adenomas, and variable in hepatocellular carcinomas and hepatoblastomas. Non-neoplastic, noncirrhotic liver was present in 50 cases; all were positive for albumin mRNA with variable staining, which was usually more intense than in the neoplasms. A zonal pattern of staining was present in 49 (98%) of these, with more intense staining within acinar zone 1 and least in zone 3. This study shows that albumin mRNA is a specific marker of hepatocellular differentiation but may be present in extrahepatic germ cell tumors with hepatoid features. For primary hepatocellular carcinomas, in situ hybridization for albumin mRNA is a useful adjunct diagnostic method.

The terms chronic active hepatitis (CAH), chronic persistent hepatitis (CpH), and chronic lobular hepatitis (CLH) have become obsolete, and their use without further specifications should be discontinued. This recommendation has become necessary because these names have changed from descriptive terms, intended for grading, to terms that are used either as morphologic diagnoses or disease designations or both, depending on individual preferences. Because this practice has caused serious misunderstandings, many authors and two international groups have recommended the use of a clear etiologic terminology. For the reporting practice of pathologists, we recommend that the pathologist routinely sign out biopsy samples with features of chronic hepatitis by indicating etiology, grade, and stage. An example would be autoimmune hepatitis, severe, stage 3. The stage in this case would indicate the presence of well-developed septal fibrosis but no nodular regeneration. Obviously, for the etiologic diagnosis, morphologic findings must be integrated with clinical and laboratory data. If this information is not available, clear morphologic diagnoses should be reported. Thus, instead of CPH, the diagnosis should be portal hepatitis, cause undetermined. This reporting practice eliminates ambiguous terminology and avoids the risk of inappropriate treatment as might occur, for example, when a term such as CAH is used to describe Wilson's disease and is misunderstood to mean autoimmune hepatitis. For a transitional period and to facilitate relearning, the terms CAH, CPH, and CLH can be reported in parentheses behind the etiologic diagnosis.

Whereas the histologic findings in clinically "chronic" autoimmune hepatitis have been well established, with piecemeal necrosis as a hallmark lesion, the histologic findings of clinically "acute" or recent-onset autoimmune hepatitis remain undefined. The goal of this study was to define more fully the liver histomorphology in patients with recent-onset autoimmune hepatitis. Twenty-six patients were identified at our institution who had well-characterized autoimmune hepatitis and had undergone a liver biopsy within 6 months of clinical presentation. A detailed histologic evaluation revealed evidence of chronic liver disease in 25 (of 26) patients despite the lack of correlating clinical chronicity. The histologic evidence of chronicity included, in addition to a portal lymphoplasmacytic infiltrate, bridging (septal) fibrosis (11 patients) and overt cirrhosis (four patients). Eighteen of these 25 cases with evidence of chronicity also showed zone 2 and 3 lobular hepatitis, including disarray and hepatocyte necrosis. A single case showed lobular hepatitis with confluent hepatocyte necrosis (submassive hepatocellular necrosis), but no evidence of chronic liver disease. Although autoimmune hepatitis remains in the differential diagnosis of lobular hepatitis, these data show that most patients with autoimmune hepatitis who undergo biopsy early in its clinical course will have histologic evidence of chronic liver disease. Most of these patients probably have a lobular "flare" in disease activity, which likely precipitated the clinical presentation. The findings herein reinforce the concept that autoimmune hepatitis is by definition a chronic disease and supports the proposal that the modifier "chronic" be eliminated from autoimmune hepatitis.