Search

The work of liver stem cell biologists, largely carried out in rodent models, has now started to manifest in human investigations and applications. We can now recognize complex regenerative processes in tissue specimens that had only been suspected for decades, but we also struggle to describe what we see in human tissues in a way that takes into account the findings from the animal investigations, using a language derived from species not, in fact, so much like our own. This international group of liver pathologists and hepatologists, most of whom are actively engaged in both clinical work and scientific research, seeks to arrive at a consensus on nomenclature for normal human livers and human reactive lesions that can facilitate more rapid advancement of our field.

All 684 post-orthotopic liver transplantation (OLT) liver biopsies performed at the Royal Free Hospital (RFH) between 1988 and 1993, from 120 patients, were reviewed in order to try to define the relative importance of the histological features of immunosuppression-responsive cellular rejection. Twenty histological features considered to be possible contributors to the diagnosis of cellular rejection were documented in a binary (present/absent) fashion. These features in 106 biopsy specimens obtained 1 to 8 days after OLT were analyzed using stepwise logistic discriminant analysis. All clinical and treatment records were reviewed, and each biopsy specimen was assigned to a diagnostic category depending on these records and follow-up information. Important determinants of the histological diagnosis of cellular rejection (which occurred in 84 of the 106 cases) were moderate/severe mixed portal inflammation, eosinophils, endotheliitis, and bile duct damage. When these all occurred together, the odds of rejection increased 3.6-fold. The original histological diagnosis was recorded, and each biopsy specimen showing cellular rejection was regarded according to the specific criteria of Snover et al., Demetris et al., and a novel RFH scoring system. The latter consists of evaluating portal inflammation, endotheliitis, eosinophils, and bile duct damage, each on a 0 to 3 scale (none, mild, moderate, or severe, respectively) and summation. The resulting cellular rejection score thus can range from 0 to 12. The agreement between the different scoring systems was analyzed using K statistics, and there was good concordance (K, 0.64 to 0.78), despite different histological criteria being used to derive each score. Each system showed a similar degree of sensitivity (87% to 96%). The specificity ranged from 59% to 77%. We conclude that the histological diagnosis of cellular rejection relies mainly on the previously described features of mixed portal inflammation, endotheliitis, eosinophils, and duct damage. There is scope for unification and simplification of the existing grading systems, which depend on differing criteria, and we suggest one such scheme.

Fibrous stenosis of hepatic venules and other features of venous outflow obstruction, including zone 3 congestion and hemorrhage, are sometimes seen after orthotopic liver transplantation. similar changes associated with endothelial damage have recently been ascribed to azathioprine toxicity and may be forerunners of chronic rejection. Other potential causative agents such as viral hepatitis have yet to be considered. We reviewed 49 liver biopsy specimens from 21 consecutive patients after orthotopic liver transplantation, in whom full data including further follow-up biopsy samples were available. Hepatic venous stenosis was identified in seven patients who had received azathioprine and two additional patients in whom this change could not be ascribed to azathioprine. Stenosis was always associated with zone 3 hemorrhage and congestion and was first noted between 5 and 30 days after transplantation in all but two cases; in these two patients they were first noted after 72 and 133 days. Cellular rejection, including endotheliitis involving terminal hepatic venules, was found in five of the seven patients who had received azathioprine. Chronic (ductopenic) rejection was not seen during a follow-up period of between 97 and 540 days. In three of the nine patients with hepatic venular stenosis, zone 3 changes persisted, and in two of these azathioprine could not be held responsible. Of the 12 patients without hepatic venular stenosis, 10 had received azathioprine. Two of these 12 patients had peliosis-like foci but no other vascular abnormalities. Both also had moderate cellular rejection. Hepatic venular stenosis was found in 43% of patients after liver transplantation; this was usually associated with azathioprine administration and concomitant cellular rejection.(ABSTRACT TRUNCATED AT 250 WORDS)

Although current literature contains many cases of putative premalignant hepatocellular proliferations and small hepatocellular carcinomas, no consistent nomenclature and diagnostic criteria have been put forward to describe them. These nodules, which are being detected by radiographic techniques in cirrhotic livers and removed during transplantation procedures, represent a new and challenging histologic spectrum of liver pathology. In this study, a multinational panel of five liver pathologists reviewed 23 such nodules and were able to reach a consensus on the diagnostic criteria and to devise a standard nomenclature to describe the histologic lesions. We recommend that benign nodules showing little histologic difference from cirrhotic nodules be classified as regenerative or macroregenerative, and nodules with atypical features not diagnostic of carcinoma be classified as borderline. Such standardization should facilitate further study of the pathologic features and clinical behavior of these lesions.

To determine the histologic pattern of hepatitis C, 54 liver biopsy specimens from 45 patients with a clinicopathological diagnosis of hepatitis C were studied. All patients were seropositive for antibody to hepatitis C virus by second-generation testing. Both transfusion-related and sporadic cases were included. More than half the samples showed chronic hepatitis without cirrhosis, whereas 44% showed developing or fully established cirrhosis. A histological pattern of mild chronic hepatitis with portal lymphoid follicles and varying degrees of lobular activity was found in many of the patients. Lymphoid aggregates or follicles were seen in 78% of biopsy specimens, but aggregates, less prominent than in hepatitis C, were also seen in 14 of 27 samples (52%) from patients with hepatitis B. We conclude that a characteristic histological pattern exists in chronic hepatitis C, that this pattern is not always found and that prominent lymphoid follicles, though not unique to hepatitis C, provide a useful diagnostic clue.

Three tamarins (Saguinus labiatus), two of which had previously been infected with hepatitis A virus and parenteral non-A, non-B hepatitis, were inoculated intravenously with the agent of GB hepatitis. All three animals developed alanine aminotransferase abnormalities 2 weeks after inoculation. Peak alanine aminotransferase levels were recorded 4 weeks postinoculation. These declined thereafter but continued to fluctuate at abnormal levels for 32 weeks. Liver biopsies showed liver cell swelling and inflammation with focal necrosis. Portal tracts and areas around central veins were heavily infiltrated with mononuclear cells. A fourth animal (no previous exposure to hepatitis viruses) inoculated with GB was killed on Day 15 postinoculation. Serum and extracts of liver and feces from this day were used as inocula for three other animals. Only the serum and liver extract transmitted GB hepatitis. The fecal specimen did not transmit and a fecal extract taken at a later date from another animal was also noninfectious. GB hepatitis virus is distinct from the viruses causing Type A and blood-borne non-A, non-B-hepatitis. Although the virus is present in serum and has previously been transmitted per os, it is not shed in feces.

beta 2-Microglobulin display was examined in 131 liver biopsies from patients with acute and chronic type B hepatitis, using an indirect immunoperoxidase method. Enhanced expression of beta 2-microglobulin on hepatocyte membranes was observed in patients with acute hepatitis, chronic active hepatitis with moderate to severe activity and cirrhosis, when compared with normal liver. In acute hepatitis, beta 2-microglobulin-positive hepatocytes were mainly observed in perivenular areas in association with bridging necrosis. In chronic hepatitis, beta 2-microglobulin-positive hepatocytes were observed mainly in periportal zones and in some areas of lobular activity. Diffuse-enhanced display of beta 2-microglobulin on hepatocytes was observed in 5 of 6 patients treated with lymphoblastoid interferon as part of a trial of antiviral therapy. The mechanism by which beta 2-microglobulin display is enhanced on hepatocytes in patients not treated with interferon is uncertain. However, display of beta 2-microglobulin on hepatocytes probably reflects display of HLA-A, B and C antigens and may influence the course of hepatitis B virus infection by increasing susceptibility of the affected cells to T cell-mediated immune attack.

Sixty-nine patients with chronic active hepatitis without cirrhosis were studied to define the prognostic implications of bridging necrosis of various types. There were 19 patients without bridging necrosis compared with 50 patients with bridging necrosis. The two groups did not differ significantly at presentation in age, sex, clinical or laboratory features. In the group without bridging necrosis, no patient died from the disease and none of 13 having a later biopsy developed cirrhosis. In the group with bridging necrosis, one patient died from hepatic failure and 7 of 36 developed cirrhosis (19%). When analyzed statistically, a significant (p less than 0.05) relationship is seen between increasing severity of initial lesion and the subsequent development of cirrhosis. It is concluded that patients with piecemeal necrosis without bridging should not be grouped together with patients with bridging necrosis or cirrhosis when considering management decisions.