Adenomatous hyperplasia of the liver as a precancerous lesion

Effects of different stocking densities on organ development, blood biochemical indices, and antioxidative status of breeder pigeons during the rearing period

The present experiment was conducted to investigate the effect of different stocking densities on the organ development, blood biochemical indices, and antioxidative status of breeder pigeons during the rearing period. A total of 280 (half male and half female) 40-day-old young pigeons were allocated into 4 groups, including 3 experimental groups (in compartments of the flying room): the high stocking density (HSD) (0.308 m3/bird), standard stocking density (SD) (0.616 m3/bird), and low stocking density (LSD) (1.232 m3/bird) and a caged control (0.04125 m3/bird). The results showed that the contents of corticosterone and heat shock protein 70 in males and the corticosterone content in females were higher in the control than in the other groups. The relative weight of liver, lung, and gizzard in males of the HSD group was the highest among the 4 treatments, whereas the abdominal fat index in the control group was higher than those in the other 3 treatments. Body weight and the relative weight of liver and abdominal fat in female pigeons in HSD group increased significantly. The levels of serum urea nitrogen and uric acid in pigeons of LSD group increased significantly, while the concentration of total cholesterol and the activity of alanine aminotransferase were higher in the control group. Ion (K+, Ca2+, and Na+) concentrations in female pigeon serum were also elevated in the control. The activity of antioxidant enzymes, including the total antioxidant capacity, superoxide dismutase, and glutathione peroxidase in pigeon breast muscle and liver had different degrees of inhibition when the space room was crowded. Moreover, the level of malondialdehyde in the liver of male caged pigeons was higher than that in the other treatments. In summary, rearing in cages or at a high density caused stress responses in the breeder pigeons. The stocking density of breeder pigeons during the rearing period should be ranged from 0.616 m3/bird to 1.232 m3/bird.

Radiofrequency ablation of high-grade dysplastic nodules

High-grade dysplastic nodules (HGDNs) are known to be premalignant lesions of hepatocellular carcinoma (HCC). We devised a model to estimate the long-term survival benefit of treating HGDNs by radiofrequency ablation (RFA) (Group I), as compared with regular follow-up and timely treatment by resection (Group II). A hypothetical 60-year-old compensated patient with cirrhosis was assumed. The system being modeled was assumed to be a simple Markov process, and state transition probabilities were given as parameters. Data used for simulation were obtained by a systematic review of the literature. The reported overall malignant transformation rates of HGDNs ranged from 12.5% to 80.8%, and were assumed to be 20%, 50%, and 80% using the best, moderate, and worst scenarios for Group II, respectively. The 5-year overall survival benefit of Group I compared with Group II was calculated by summing the detrimental effect of overtreatment and the beneficial effects of avoiding operative mortality. When the overall malignant transformation rate was set at 20%, 50%, or 80% the expected additional 5-year overall survival benefits of Group I compared with Group II were -0.05%, 0.20%, and 0.47%, respectively, and the corresponding additional 10-year overall survival benefits were 0.03%, 0.33%, and 0.55%, respectively. One-way sensitivity analysis showed that Group I was preferable to Group II in terms of 5-year overall survival when the 5-year overall malignant transformation rate was greater than 25.9%.

CONCLUSION

No definite evidence indicates that the treatment of HGDNs by RFA provides additional long-term overall survival benefit as compared with regular follow-up and timely treatment. The findings of the present study concur with the present American Association for the Study of Liver Diseases guidelines.

Gd-EOB-DTPA enhanced micro-MR imaging of hepatic tumors in H-ras 12V transgenic mice

RATIONALE AND OBJECTIVES

The aims of this study were to evaluate the morphologic characteristics and growth pattern of hepatic tumors in H-ras 12V transgenic (TG) mice using a micro-magnetic resonance (MR) system and to assess the usefulness of gadolinium ethoxybenzyl diethylenetriamine penta-acetic acid (Gd-EOB-DTPA) enhancement for the detection of hepatic tumors in these mice.

MATERIALS AND METHODS

Hepatocellular carcinoma lines were established to allow insertion of the H-ras 12V transgene under the control of the albumin enhancer/promoter. Seven H-ras 12V TG mice and four wild-type mice were included in this study. The mice underwent various MR imaging examinations, including T1-weighted imaging (repetition time, 300 ms; echo time, 11 ms), Gd-EOB-DTPA-enhanced T1-weighted imaging (dose, 0.025 mmol/kg), and T2-weighted imaging (repetition time, 3500 ms; echo time, 36 ms), with a 4.7-T MR scanner, at 4, 6, 8, and 9 months of age. All mice were euthanized after the final MR imaging procedure, except for one TG mouse and two wild-type mice that were euthanized after MR imaging procedures at 4 months of age. For imaging analysis, the tumor characteristics in each MR sequence, including tumor size, number, and signal intensity (SI), were recorded, and the contrast-to-noise ratio and contrast enhancement ratio were calculated to quantify the SI of the tumor. The MR images were correlated with the findings of histopathologic examinations.

RESULTS

No tumors were detected in the four wild-type mice. In the six TG mice, a total of 67 tumors were found in histopathologic specimens obtained at 9 months of age. Of the 67 tumors, 62 were detected on Gd-EOB-DTPA-enhanced T1-weighted images with fat saturation. The majority of hepatic tumors showed high SI on T1-weighted images without fat saturation. The SI diminished on T1-weighted images with fat saturation. The tumor contrast-to-noise ratio for Gd-EOB-DTPA-enhanced T1-weighted imaging was significantly better than that for the other sequences. The tumors were histopathologically confirmed as hepatocellular adenomas (n = 32) and well-differentiated hepatocellular carcinomas (n = 35).

CONCLUSIONS

Micro-MR imaging can reveal the characteristics of hepatic tumors in a live murine model. Gd-EOB-DTPA-enhanced T1-weighted imaging is helpful in the detection of hepatic tumors in H-ras 12V TG mice.

Hepatocellular carcinoma: epidemiology, surveillance, and diagnosis

Hepatocellular carcinoma (HCC) is increasing in incidence in many countries, and is the most common cause of death in patients with cirrhosis. With regular surveillance, small early HCC lesions can be identified. An algorithm has been developed that allows for diagnosis of these lesions. Very early HCC lesions have high cure rates with appropriate treatment. If all these factors are in place most HCCs can be cured.

Hepatocarcinogenesis: multistep changes of drainage vessels at CT during arterial portography and hepatic arteriography--radiologic-pathologic correlation

PURPOSE

To clarify the changes that occur in drainage vessels of dysplastic nodules and hepatocellular carcinoma (HCC) during hepatocarcinogenesis by using computed tomography (CT) during arterial portography (CTAP) and CT during hepatic arteriography (CTHA), with histologic findings as the reference standard.

MATERIALS AND METHODS

Institutional ethics committee approval and informed consent were obtained. According to the findings at CTAP and CTHA, 46 surgically resected hepatocellular nodules were classified into three types: type A (n = 18) (equivalent or decreased portal perfusion compared with background liver at CTAP, decreased arterial perfusion, and no corona enhancement [perinodular contrast material drainage] at CTHA), type B (n = 13) (no portal perfusion, increased arterial perfusion, and thin (< or = 2-mm) corona enhancement), or type C (n = 15) (no portal perfusion, increased arterial perfusion, and thick (> 2-mm) corona enhancement). We compared the histopathologic features and microangioarchitecture between the types.

RESULTS

Type A nodules histologically consisted of dysplastic nodules and well-differentiated HCC; type B and C nodules were moderately differentiated HCC. Replacing growth was commonly observed in type A nodules, whereas compressing growth was more frequently seen in types B and C. Sixty percent of type C nodules had a fibrous capsule. There were significantly fewer intranodular hepatic veins in types B and C. Serial pathologic slices demonstrated continuity from intranodular capillarized sinusoids to hepatic veins in type A nodules and to surrounding hepatic sinusoids in type B nodules. In type C nodules, intranodular capillarized sinusoids were connected to extranodular portal veins either directly or through portal venules within the fibrous capsule.

CONCLUSION

Drainage vessels of HCC change from hepatic veins to hepatic sinusoids and then to portal veins during multistep hepatocarcinogenesis.

Bile ductular cell reaction with senescent hepatocytes in chronic viral hepatitis is lost during hepatocarcinogenesis

Cellular senescence is defined as irreversible cell arrest and could work as a safeguard against tumorigenesis. This mechanism was examined in chronic viral hepatitis-related hepatocarcinogenesis. By using surgical resected or wedge biopsied liver specimens from 87 chronic viral hepatitis patients in whom 35 neoplastic nodules (dysplastic nodules and hepatocellular carcinoma) were complicated, P21 expression and senescence-associated beta galactosidase activity, a marker of senescence, were examined. All of these neoplastic nodules harbored portal tracts within the tumors. Hepatocytes expressing senescence markers and cytokeratin (CK)7-positive bile ductules including hepatic progenitor-like cells were increased in periseptal areas in cirrhosis. Interestingly, these cells appeared to form an anatomical complex that was completely lost in the periportal areas within the neoplastic nodules. In one-third of the neoplastic nodules, CK7-positive small neoplastic hepatocytes resembling hepatic progenitor cells proliferated zonally around the portal tracts. In conclusion, loss of a complex of senescent hepatocytes and ductular cell including hepatic progenitor-like cells in the periportal or periseptal areas may be associated with emergence of neoplastic hepatocytes and their proliferation followed by neoplastic nodules arising in liver cirrhosis. Zonal proliferation of CK7-positive small neoplastic hepatocytes resembling hepatic progenitor cells may develop during early hepatocarcinogenesis.

Hepatocellular adenoma in advanced-stage fatty liver disease

Hepatocellular adenomas are defined as benign hepatocellular neoplasms occurring in otherwise near normal liver and adenomatosis as 10 or more such lesions. We present a case of a 45-year-old man with radiological adenomatosis, histologically confirmed with resection of one lesion, arising within advanced-stage nonalcoholic fatty liver disease (nearly cirrhotic). Hepatocellular adenomas have recently been divided into four categories and the lesion in the present case had morphologic and immunohistochemical features of an inflammatory hepatocellular adenoma. These findings demonstrate that, in contrast to the current dogma, nodules within advanced-stage liver disease may rarely be best classified as adenomas. This should be considered in the radiological differential diagnosis when assessing a patient's suitability for transplantation.

Multistep human hepatocarcinogenesis: correlation of imaging with pathology

Hepatocellular carcinoma (HCC) is one of the most common malignancies worldwide. The majority of HCCs develop in cirrhotic livers, and the early detection and characterization of this entity is very important. Pathologically, human HCC develops in a multistep fashion in the following sequence: from low-grade dysplastic nodule (LGDN), to high-grade dysplastic nodule (HGDN), early HCC, well-differentiated HCC, nodule-in-nodule HCC, and, finally, to moderately differentiated HCC. Differentiation between early HCC and DN is the most important issue in the clinical setting. CT during hepatic angiography (CTHA) and CT during arterial portography (CTAP) are the most sensitive tools in the differentiation of premalignant/borderline lesions (LGDN and HGDN) and early HCC. Recent progress in imaging modality, especially Sonazoidenhanced US and Gd-EOB-DTPA MRI, is starting to play a very important role in the imaging of multistep hepatocarcinogenesis, resulting in changing the therapeutic strategy of these nodular lesions associated with liver cirrhosis.

The overexpression of polycomb group proteins Bmi1 and EZH2 is associated with the progression and aggressive biological behavior of hepatocellular carcinoma

Polycomb-group proteins Bmi1 and EZH2 are involved in the malignant transformation and biological aggressiveness of several human carcinomas. We herein examined the significance of the Bmi1 and EZH2 expression in hepatocellular carcinoma (HCC) and its preneoplastic lesions, dysplastic nodules. The expression of Bmi1 and EZH2 were examined immunohistochemically in HCC (n=27) and dysplastic nodules (n=14), and combined hepatocellular and cholangiocarcinoma (HC-CC) (n=14). The effect of Bmi1 and EZH2 knockdown was examined in cultured HCC cells (HuH7 and HepG2) using siRNA. It was determined that Bmi1 was constantly expressed in cholangiocytes, but not in hepatocytes, and EZH2 was detected in neither cholangiocytes nor hepatocytes. Bmi1 and EZH2 were overexpressed in HCC and more extensively in HC-CC (P<0.01). Interestingly, Bmi1 and EZH2 were not overexpressed in the dysplastic nodules. The expression of Bmi1 and EZH2 was heterogeneous and associated with vascular infiltration, the histological grades, and the cell proliferation activity in HCC and HC-CC. In cultured carcinoma cells overexpressing Bmi1 and EZH2, knockdown of Bmi1 and EZH2 resulted in decreased cell proliferation activities. Therefore, the overexpression of polycomb-group proteins Bmi1 and EZH2 is associated with the malignant progression of HCC, thereby reflecting the aggressive biological behavior in HCC and HC-CC.

Macro-regenerative nodules in biliary atresia: CT/MRI findings and their pathological relations

AIM: To describe the radiological findings of a macro-regenerative nodule (MRN) in the liver of pre-transplantation biliary atresia (BA) patients and to correlate it with histological findings.

METHODS: Between August 1990 and November 2007, 144 BA patients underwent liver transplantation (LT) at our institution. The pre-transplantation computer tomography (CT) and magnetic resonance imaging (MRI) findings were reviewed and correlated with the post-transplantation pathological findings.

RESULTS: Nine tumor lesions in 7 patients were diagnosed in explanted livers. The post-transplantation pathological findings showed that all the lesions were MRNs without malignant features. No small nodule was detected by either MRI or CT. Of the 8 detectable lesions, 6 (75%) were in the central part of the liver, 5 (63%) were larger than 5 cm, 5 (63%) had intra-tumor tubular structures, 3 (38%) showed enhancing fibrous septa, 3 (38%) had arterial enhancement in CT, one (13%) showed enhancement in MRI, and one (13%) had internal calcifications.

CONCLUSION: Although varied in radiological appearance, MRN can be differentiated from hepatocellular carcinoma (HCC) in most of BA patients awaiting LT. The presence of an arterial-enhancing nodule does not imply that LT is withheld solely on the basis of presumed malignancy by imaging studies. Liver biopsy may be required in aid of diagnostic imaging to exclude malignancy.

Vascular endothelial growth factor, its receptor Flk-1, and hypoxia inducible factor-1alpha are involved in malignant transformation in dysplastic nodules of the liver

Dysplastic nodules (DNs) are regarded as a premalignant lesion of hepatocellular carcinoma (HCC). Sinusoidal capillarization and unpaired arteries are reported in HCC and also to a lesser degree in DN. However, the mechanism and significance of these vascular alterations remain unclear. In this study, these vascular changes were examined with respect to vascular endothelial growth factor (VEGF) and its receptors (Flt-1 and Flk-1), hypoxia inducible factor-1alpha (HIF-1alpha), and CD34, by using 20 surgically resected cases of DNs and 36 cases of conventional HCC. The expression of these molecules was examined immunohistochemically. Although sinusoidal capillarization characterized by CD34 expression was found diffusely in HCC, such changes were found mainly in the areas around the portal tracts and also in other areas in DNs (focal in 6 cases, zonal in 7 cases, and extensive distribution in 7 cases). These capillarized areas were frequently associated with unpaired arteries, and the infiltration of neoplastic hepatocytes into the portal tracts and loss of reticulin fibers in DNs, particularly those with a zonal and extensive distribution. VEGF was diffusely expressed in neoplastic hepatocytes of DNs and HCC. Interestingly, Flk-1 and HIF-1alpha were mostly expressed in endothelial cells and neoplastic hepatocytes in the capillarized areas around portal tracts in DNs, respectively. In conclusion, the capillarized areas with increased numbers of unpaired arteries in DNs may represent an early malignant transformation. Increased expression of Flk-1 and HIF-1alpha associated with VEGF may be involved in sinusoidal capillarization and the increased numbers of unpaired arteries in these areas.

Minute scirrhous hepatocellular carcinomas undergoing different carcinogenetic processes

Scirrhous hepatocellular carcinoma (scirrhous HCC) is a rare histological subtype of HCC characterized by marked fibrosis along the sinusoid spaces. Carcinogenetic processes and pathological features at earlier stages of scirrhous HCC remain unclarified. In the present report two cases of minute scirrhous HCC suggesting different carcinogenesis, are described. The first case involved a 54-year-old man with liver cirrhosis related to HCV infection. This patient died of ruptured splenic aneurysm. At autopsy a hepatic tumor measuring 1.8 cm was found, and this tumor had a nodule-in-nodule appearance. Histologically, the inner part of the tumor was well-differentiated HCC with prominent collagen fiber deposition along the sinusoids (scirrhous HCC), whereas the outer part was a high-grade dysplastic nodule. The other patient was a 75-year-old woman who died of hepatic failure due to liver cirrhosis probably related to non-alcoholic steatohepatitis. At autopsy a hepatic tumor (1.2 cm in diameter) was incidentally found in the cirrhotic liver, and was histologically scirrhous HCC without dysplastic nodule elements. Carcinoma cells proliferated along the cirrhotic fibrous septa and replaced regenerative nodules. These two cases suggested that scirrhous HCC could occur in dysplastic nodules (the former case) and also develop de novo in cirrhotic liver (the latter case).

Indeterminate small, low-attenuating hepatocellular nodules on helical CT in patients with chronic liver disease: 2-year follow-up

To evaluate the clinical significance of indeterminate, small, low-attenuating nodular lesions on helical dynamic computed tomography (CT) in chronic liver diseases, CT images were reviewed retrospectively in 281 patients. Indeterminate, low-attenuating nodular lesions less than 20 mm in diameter were followed for 24 to 35 months. Of 127 nodules in 73 patients, 21 nodules turned out to be hepatocellular carcinomas (16%), 25 nodules (20%) became larger, while the remaining 81 nodules (64%) remained unchanged or disappeared. Some low-attenuating nodules larger than 10 mm in diameter may develop into hepatocellular carcinoma.

[Epidemiology, natural history and pathogenesis of hepatocellular carcinoma]

Hepatocellular carcinoma is one of the most prevalent tumors worldwide and its incidence is increasing due to hepatitis C virus infection. Other etiologic factors are hepatitis B virus infection, alcoholic liver disease and hemochromatosis. This tumor mainly develops in cirrhotic livers that are true precancerous states. Although mechanisms of hepatocarcinogenesis remain badly known, some signaling pathways are frequently deregulated: inactivation of the p53 tumor suppressor factor in 25% of HCC, activation of the Wnt signaling and the telomerase immortalization enzyme in most of tumors. Hepatitis viruses play a direct oncogenic role by interaction between viral proteins and cellular ones, which control cell homeostasis, or by integration of hepatitis B virus genome into the host genome. Furthermore, hepatitis viruses play an indirect oncogenic role by chronic inflammation and hepatocyte regeneration related to viral hepatopathy. In a near future, a better understanding of virus-specific oncogenic mechanisms should allow us to set up innovative preventive and curative therapeutic strategies.

Classification of proliferative hepatocellular lesions in harlan sprague-dawley rats chronically exposed to dioxin-like compounds

Over the years, the most appropriate classification scheme for nodular proliferative lesions of the hepatocyte has been heavily debated. In the most recent guidelines there appears to be a consensus for classifying these lesions as hepatocellular adenoma, hepatocellular carcinoma, or regenerative hyperplasia. Also, large foci of cellular alteration may appear somewhat nodular. Some nodular hepatocellular lesions from a group of 7 studies of dioxin and dioxin-like compounds conducted by the National Toxicology Program did not readily fit into these categories. Some of these lesions had morphologic features consistent with hyperplasia. However, there was not sufficient morphological or biological evidence to conclude that the entire response was regenerative. In other instances, these lesions had some features resembling adenoma, but contained a prominent component of biliary epithelium and/or oval cells. This component does not appear to be well described in the literature, and while its presence suggested a nodule to be nonneoplastic, this is inconclusive. This paper describes the morphology of these lesions, as well as the diagnostic approach taken in this series of studies.

Viral hepatitis and hepatocellular carcinoma

BACKGROUND

Hepatocellular carcinoma (HCC) is one of the most common malignant tumors in the world. The incidence of HCC varies considerably with the geographic area because of differences in the major causative factors. Chronic hepatitis B and C, mostly in the cirrhotic stage, are responsible for the great majority of cases of HCC worldwide. The geographic areas at the highest risk are South-East Asia and sub-Saharan Africa, here hepatitis B is highly endemic and is the main cause of HCC. In areas with an intermediate rate of HCC such as Southern Europe and Japan, hepatitis C is the predominant cause, whereas in low rate areas such as Northern Europe and the USA, HCC is often related to other factors as alcoholic liver disease. There is a rising incidence in HCC in developed countries during the last two decades, due to the increasing rate of hepatitis C infection and improvement of the clinical management of cirrhosis.

METHODS

This article reviews the literature on hepatitis and hepatocellular carcinoma. The Medline search was carried out using these key words and articles were selected on epidemiology, risk factors, screening, and prevention of hepatocellular carcinoma.

RESULTS

Screening of patients with advanced chronic hepatitis B and C with hepatic ultrasound and determination of serum alfa-fetoprotein may improve the detection of HCC, but further studies are needed whether screening improves clinical outcome. Hepatitis B and C viruses (HBV/HCV) can be implicated in the development of HCC in an indirect way, through induction of chronic inflammation, or directly by means of viral proteins or, in the case of HBV, by creation of mutations by integration into the genome of the hepatocyte.

CONCLUSION

The most effective tool to prevent HCC is avoidance of the risk factors such as viral infection. For HBV, a very effective vaccine is available. Preliminary data from Taiwan indicate a protective effect of universal vaccination on the development of HCC. Vaccination against HBV should therefore be a health priority. In patients with chronic hepatitis B or C, interferon-alfa treatment in a noncirrhotic stage is protective for HCC development in responders, probably by prevention of cirrhosis development. When cirrhosis is already present, the protective effect is less clear. For cirrhosis due to hepatitis B, a protective effect was demonstrated in Oriental, but not in European patients. For cirrhosis due to hepatitis C, interferon-alfa treatment showed to be protective in some studies, especially in Japan with a high incidence of HCC in untreated patients. Virological, but also merely biochemical response, seems to be associated with a lower risk of development of HCC. As most studies are not randomized controlled trials, no definitive conclusions on the long-term effects of interferon-alfa in HBV or HCV cirrhosis can be established. Especially in hepatitis C, prospective studies should be performed using the more potent reference treatments for cirrhotics, namely the combination of peginterferon and ribavirin.

Critical evaluation of the different staging systems for hepatocellular carcinoma

BACKGROUND

Diagnostic and therapeutic options for hepatocellular carcinoma (HCC) have improved substantially in recent years. A number of new palliative and potentially curative treatment strategies are now available. However, evaluation of the therapeutic modalities and assessment of the prognosis of HCC remain difficult owing to the lack of consensus on a single staging system and the availability of a number of new staging systems, each claiming to be the most appropriate.

METHODS

The most frequently used staging systems for HCC are presented here. Their ability to stratify patients into different treatment groups and to define prognosis are discussed. In addition, the advantages and disadvantages of each system are analysed.

RESULTS AND CONCLUSION

None of the currently used staging systems fulfils all the requirements for stratification of patients with HCC into groups of different prognosis and therapeutic recommendations. An international agreement on a single staging system is urgently needed in order to permit comparable randomized clinical trials. Only in this way will the outcome for those with HCC be improved.

Immunohistochemical assessment of proliferating cell nuclear antigen in primary hepatocellular carcinoma and dysplastic nodules

A complementary way for the assessment of HCC prognosis is represented by the analysis of molecular markers. Thus, immunohistochemical assessment of proliferation can describe tumor aggressiveness, probability of local recurrence or metastasis potential, being very useful for the assessment of recurrence-free survival and survival until death. The aim of our study was to assess proliferating cell nuclear antigen activity in HCC and dysplastic nodules as compared with surrounding non-neoplasic areas. Immunohistochemical techniques were thus performed on the samples obtained by ultrasound-guided liver biopsies or intraoperative biopsies, in 32 patients with HCC, as well as in 3 patients with dysplastic nodules occurring in liver cirrhosis. Expression of PCNA within extranodular areas of the HCC patients in the absence or presence of cirrhosis, was increasing from 40% to 70%, respectively. PCNA expression further increased within intranodular areas of dysplastic nodules and HCC, to 100% and 96.88%, respectively. A progressive increase of the mean values of PCNA-LI was also observed from extranodular areas without or with cirrhosis, towards intranodular areas of dysplastic nodules and HCC (4.2%, 6.8%, 27.9%, 31.9%, respectively). Dysplastic nodules can thus be considered lesions with a high-proliferation rate, representing an early stage of hepatocarcinogenesis. This supported the current recommendations for borderline hepatocellular nodules identified by ultrasound, which indicate an aggressive treatment similar to malignant lesions. In summary, we demonstrated a progressively increasing rate of cellular proliferation, from extranodular non-neoplasic areas to intranodular areas (dysplastic nodules and HCC), as reflected by an increased expression of proliferating cell nuclear antigen labelling index.

Pathology of hepatocellular carcinoma and its precursors using proton magnetic resonance spectroscopy and a statistical classification strategy

AIM

Apply the statistical classification strategy (SCS) to magnetic resonance spectroscopy (MRS) data from liver biopsies and test its potential to discriminate between normal liver, cirrhotic nodules and nodules of hepatocellular carcinoma with a high degree of accuracy.

METHODS

Liver tissue specimens from 54 patients undergoing either partial (hemi) or total hepatectomy were analysed by one-dimensional proton MRS at 8.5 Tesla. Histologically, these specimens were confirmed as normal (n=31), cirrhotic (n=59), and hepatocellular carcinoma (HCC, n=32). Diagnostic correlation was performed between the MR spectra and histopathology. An SCS was applied consisting of pre-processing MR magnitude spectra to identify spectral regions of maximal discriminatory value, and cross-validated linear discriminant analysis.

RESULTS

SCS applied to MRS data distinguished normal liver tissue from HCC with an accuracy of 100%. Normal liver tissue was distinguished from cirrhotic liver with an accuracy of 92% and cirrhotic liver was distinguished from HCC with an accuracy of 98%.

CONCLUSIONS

SCS applied to proton MRS of liver biopsies provides a robust method to distinguish, with a high degree of accuracy, HCC from both cirrhotic and normal liver.

Computed tomography and magnetic resonance imaging evaluation of liver cancer

Focal liver lesions occur commonly and with varying histology, each requiring radically different management. There are a multitude of imaging modalities currently being used for detecting and characterizing focal liver neoplasms. The primary modalities include ultrasonography, computed tomography (CT), magnetic resonance imaging (MRI), and rarely, angiography. CT and MRI have benefited from rapid technologic advances, and MRI, in particular, from the advent of new contrast agents.

Dysplastic nodules and hepatocarcinogenesis

In the last decade, careful examination of explanted cirrhotic livers in liver transplant centers around the world has confirmed the findings of the earlier Japanese investigators: DNs (by this or any other name) represent hepatic, premalignant lesions in chronic liver disease. Careful examination of their gross and microscopic morphologies has led to the hypothesis of precirrhotic, spreading clonal expansions that are resistent to scarring, and that result in neoplastic islands of hepatic parenchyma. The resultant distinctive nodules, often marked by features suggestive of their clonality (such as increased pigment), are at increased risk for subsequent carcinomatous events, thereby giving rise to HCC. Specialized molecular and immunohistochemical studies confirm many aspects of this hypothesis. In suggesting that some aspects of DN pathophysiology are not integral to the carcinogenetic pathway (i.e., inhibition of HSC inactivation), this hypothesis serves a broader purpose, explaining the various settings in which early HCCs are found in cirrhotic explants and in wedge resections of radiographically defined lesions. Discrepancies between Japanese and non-Japanese investigations regarding dysplasia and early HCCs reflect not different biologic pathways but differences in detection, interpretation, and application of nomenclature. These differences may fade away as more international collaborative work brings investigators of diverse nationalities into regular contact, supporting movement toward a commonly acceptable nomenclature and set of diagnostic criteria. Ultimately, an understanding of the pathophysiology of these lesions, through more detailed molecular and physiologic studies, should lead to more efficient and available early detection, and perhaps chemoprevention approaches to hepatic malignancy.

Huge adenomatous hyperplasia of the liver

Adenomatous hyperplasia (AH) of the liver is defined as a regenerative overgrowth with limited growth potential. Patients with AH of the liver usually have cirrhosis of the liver as well. Adenomatous hyperplasia is also described as a benign nodule more than 8 mm, which is the main differentiation between AH and regeneration nodules (which are less than 8 mm). Adenomatous hyperplasias more than 20 mm is extremely rare in the clinicopathologic studies. We present two cases of extraordinarily large AH (one was 100 mm and the other, 30 mm). Both patients were alcoholic, and one also had viral hepatitis B. By clinical, biochemical, and upper gastrointestinal endoscopic examinations, we diagnosed liver cirrhosis in both. Sizable nodules were discovered in their livers using imaging studies (including ultrasonography, computed tomography, magnetic resonance imaging, and positron emission tomography), and percutaneous liver biopsies of the nodules showed their cirrhotic background. However, neither of the patients developed hepatocellular carcinoma during the follow-up period.

Magnetic resonance of focal liver lesions in hepatic cirrhosis and chronic hepatitis

Detection of focal liver nodules in patients with cirrhosis continues to be a radiologic challenge despite progressive advances in liver imaging in the past 2 decades. Patients with hepatic cirrhosis have a high predisposition to develop hepatocellular carcinoma (HCC), and the early detection and diagnosis of this tumor is very important because the most effective treatment is surgical resection, transplantation, or local ablation therapy when the tumor is small. Cirrhotic livers are mainly composed of fibrosis, together with a broad spectrum of focal nodular lesions ranging from regenerative nodules to premalignant dysplastic nodules to overt HCC. Awareness of such lesions and interpretation of imaging studies in these patients requires a critical review to detect subtle tumors, and a thorough understanding of the imaging appearance of the malignant and benign masses that can occur in the cirrhotic liver. Although the recent advances in liver imaging techniques, especially computed tomography (CT) and magnetic resonance (MR), have facilitated the detection and characterization of focal liver nodules in cirrhotic patients, discriminating between HCC and precancerous nodules remains problematic with all available imaging techniques. Nevertheless, MR imaging appears to have more potential than other imaging techniques in the study of cirrhotic patients and MR may be more appropriate than the other imaging modalities for the detection of small HCCs. In this article we review the imaging characteristics of nodular focal lesions that arise in cirrhotic livers, with special attention to MR imaging features.

Detection of nodules in liver cirrhosis: spiral computed tomography or magnetic resonance imaging? A prospective study of 88 nodules in 34 patients

Detection and characterization of all focal lesions in the liver are critical for screening patients with chronic liver disease. The aim of this prospective study was to investigate the accuracy of magnetic resonance imaging (MRI) and spiral computed tomography for the diagnosis of hepatic nodules in cirrhotic patients when compared with pathological findings of the explanted liver. From February 1997 to July 1999, 34 cirrhotic patients waiting for orthotopic liver transplantation (OLT) (mean age, 53.5 +/- 9.3 years; 24 males) were included. All patients had MRI and spiral computed tomography examinations, and findings were matched with the histological findings. Data analyses were made using the McNemar chi-square test. Mean time between radiological examination (MRI or spiral computed tomography) and OLT was 43.8 +/- 39 days. A total of 88 nodules were found in the 34 patients: 54 hepatocellular carcinoma (HCC) (mean size, 18 +/- 10 mm) in 21 patients, 22 dysplastic nodules (mean size, 10.7 +/- 4.3 mm) in 11 patients, and 12 macroregenerative nodules in 13 patients. Lesion-by-lesion analyses showed that sensitivity of MRI and spiral computed tomography for nodule, HCC or dysplastic nodule diagnosis was 44.3 and 31.8% (P = 0.02), 61.1 and 51.9% (P = 0.2), and 27.3 and 0% (P = 0.04), respectively. Patient-by-patient analyses showed no statistical difference between spiral computed tomography and MRI for nodule diagnosis. In conclusion, in patients with liver cirrhosis, MRI is more accurate than spiral computed tomography for the detection of liver nodules and dysplastic nodules. However, tumour size is always a restricting factor for these two techniques, which are unable to detect small HCC in more than 60% of cases.

A giant multiacinar macroregenerative nodule in an explanted liver

Macroregenerative nodules (MRN) have been detected with increased incidence in explanted livers since orthotopic liver transplantation (OLTx) has become a routine treatment for end-stage liver disease. Autopsy series suggest that MRN may be more common than once thought, and several studies point to the malignant potential of these lesions. With increasing waiting times for OLTx, the propensity for these premalignant lesions to arise in cirrhotic livers has important implications for the supervision of patients on OLTx waiting lists. We present here a striking example of a MRN and review a topic that is generating considerable interest.

Hepatocellular carcinoma: an overview

Hepatocellular carcinoma remains widely prevalent in tropical Africa and south-east Asia and is largely related to chronic hepatitis B virus (HBV) infection. Primary prevention by vaccination of infants at or near birth is effective but any reduction in tumour incidence cannot be expected for decades to come yet, even in those countries in which the necessary resources exist, as millions of adults remain chronically infected. Meanwhile, the incidence is rising in Japan, Mediterranean countries of Europe, Middle East and North Africa and in the USA, largely due to chronic hepatitis C virus (HCV) infection introduced by the indiscriminate use of unscreened blood and blood products in the recent past. Much has been learned from molecular biological studies on hepatocarcinogenesis incriminating the HBX gene of HBV, the core protein of HCV and a unique guanine to thymine transversion at codon 249 has been observed in cases due to aflatoxin exposure. The subject of precancerous lesions, notably adenomatous/dysplastic nodules and large-cell/small-cell change continues to be a source of much debate and the distinction of nodular lesions in cirrhosis from early carcinoma remains uncertain. Spontaneous regression of hepatocellular carcinoma is rare but it is probably immunologically mediated and treatment by activated T-lymphocytes may reduce recurrence rates after surgery. The positive identification of hepatocellular carcinoma by a liver-specific antibody has greatly facilitated the diagnosis in difficult cases.

Diagnostic and prognostic tumor markers in the gastrointestinal tract

The gastrointestinal tract is the most common site of malignancies of any anatomic system in the body. An early detection of primary tumors of the bowel, pancreas, liver, stomach, and esophagus is often difficult in asymptomatic patients and for this reason these tumors are often detected at a relatively advanced stage, when symptoms lead to a diagnostic evaluation. Furthermore, gastrointestinal tract tumors have an extremely variable prognosis; thus, the identification of new prognostic parameters may be useful for selecting patients to more tailored therapies. In this work, the main molecular, genetic, tissular, and circulating tumor markers proposed for diagnosis and prognosis of gastrointestinal malignancies are reviewed and discussed.

Hepatocellular carcinoma arising in non-alcoholic steatohepatitis

The incidence and significance of hepatocellular carcinoma (HCC) in non-alcoholic steatohepatitis (NASH) has not been previously evaluated in detail. We recently experienced a case of NASH with multicentric HCC in a female patient. At the age of 58 years, the patient was diagnosed with non-insulin-dependent diabetes mellitus, treated by insulin therapy. The patient did not drink alcohol. She was negative for all serological markers of hepatitis B and C virus infection. Because of liver dysfunction, a needle biopsy was performed at the age of 62 years, and pathological findings, such as fatty change, Mallory's body, nuclear glycogen and pericellular fibrosis, suggested a diagnosis of NASH. Subsequently, four nodules were detected in the liver by imaging. Liver biopsies were performed from each nodule. One nodule was pathologically diagnosed as a pseudolymphoma, while three other nodules were moderately differentiated HCC (10 years after the diagnosis of non-alcoholic steatohepatitis), well-differentiated HCC (11 years later) and dysplastic nodule (11 years later), suggesting multicentric occurrence of HCC. This case suggests that HCC could be a late complication of NASH.

Benign tumors of the liver

Benign tumors of the liver, less commonly encountered than metastatic or primary liver tumors, may present clinically with symptoms due to mass effect, or may be discovered incidentally during radiographic evaluation or surgical exploration for other clinical indications. Many of the lesions that result in a benign liver mass are true neoplasms, while others result from reactive proliferation of hepatocytes, biliary cells, mesenchymal or inflammatory cells. The premalignant nature or potential for malignant transformation is of concern in some of the benign tumors or tumor-like masses of the liver. In this article, benign tumors and tumor-like masses involving the adult liver are discussed with a focus on histopathology, histogenesis, and clinical significance of these interesting and unusual lesions.

Siderotic nodules in the cirrhotic liver at MR imaging with explant correlation: no increased frequency of dysplastic nodules and hepatocellular carcinoma

PURPOSE

To determine the sensitivity of magnetic resonance (MR) imaging for detection of siderotic nodules in patients with cirrhosis and whether the frequency of hepatocellular carcinoma (HCC) and dysplastic nodules is greater if siderotic nodules are present.

MATERIALS AND METHODS

MR imaging (1.5 T) was performed within 0-117 days (mean, 30 days) before liver transplantation in 77 patients. Two readers retrospectively evaluated gradient-echo (GRE) (echo time [TE], > or = 9 and 4-5 msec) and turbo short inversion time inversion-recovery or T2-weighted images for low-signal-intensity nodules. Whole-explant pathologic correlation was available in every case.

RESULTS

At explantation, 28 (36%) of 77 patients had HCC, 25 (32%) had dysplastic nodules, and nine (12%) had both; 35 (45%) patients had siderotic nodules. The sensitivity of GRE imaging with 9-msec or longer TE for the detection of siderotic nodules was 80% (28 of 35) but decreased to 31% (11 of 35) with 4-5-msec TE. Frequency of HCC was not significantly higher (P =.27) in patients with (43% [15 of 35]) than in patients without (31% [13 of 42]) siderotic nodules. Frequency of dysplastic nodules also was not significantly higher (P =.42) in patients with (37% [13 of 35]) than in patients without (29% [12 of 42]) siderotic nodules.

CONCLUSION

Sensitivity of MR imaging for the detection of siderotic nodules was improved with use of GRE pulse sequences with longer TEs of 9 msec or greater (80%) versus 4-5 msec (31%); however, there was no significant increased frequency of HCC or dysplastic nodules in patients with pathologically proved siderotic nodules.

Molecular changes in hepatocellular dysplastic nodules on microdissected liver biopsies

The genetic profile of dysplastic hepatocellular nodules arising in cirrhosis is poorly understood. We assessed loss of heterozygosity (LOH) and microsatellite instability (MI) in 10 dysplastic nodules (4 low-grade and 6 high-grade) with surrounding cirrhosis and in 10 hepatocellular carcinomas (HCC). Six microsatellite loci were selected and investigated on microdissected needle biopsies. Twenty-four (24.4%) informative loci showed allelic loss, while MI was seen in 3 loci only (3%). The most involved sites were located on chromosomes 4q (54.5%) and 8p (50%). LOH was documented in 16.6%, cirrhotic, 50% low-grade dysplastic nodules (LGDN), 83% high-grade dysplastic nodules (HGDN), and 70% malignant nodules. LOH at multiple loci was increasingly seen from cirrhotic to HGDN, but not from the latter to HCC. The fractional allelic loss (FAL) was significantly increased in dysplastic and neoplastic nodules as compared with cirrhosis (P <.01). The progressive accumulation of genetic changes in cirrhotic, dysplastic, and malignant hepatocellular nodules is in keeping with a multistep process of carcinogenesis; within this spectrum, HGDN can be considered advanced precursors of HCC.

Increased expression of vascular endothelial growth factor and angiogenesis in the early stage of multistep hepatocarcinogenesis

BACKGROUND

Hepatocellular carcinoma (HCC) is known to receive its blood supply principally from the hepatic arteries. Recent studies have reported differences in the vascular supply, especially arterial supply among low- and high-grade dysplastic nodules (DNs) (also referred to as adenomatous hyperplasia and macroregenerative nodules) and HCCs. Increased expression of vascular endothelial growth factor (VEGF) has been reported in HCC. In addition, VEGF may play an important role in the early phases of hepatocarcinogenesis.

METHODS

We immunohistochemically stained 7 low-grade DNs, 8 high-grade DNs, 11 early HCCs, 17 small HCCs, and 21 advanced HCCs with antibodies against VEGF, alpha-smooth muscle actin (to identify unpaired arteries, ie, arteries not accompanied by bile ducts, indicative of angiogenesis), CD34 (as a marker of sinusoidal capillarization), and proliferation cell nuclear antigen.

RESULTS

Expression of VEGF was found in the hepatocytes and HCC cells. The degree of VEGF expression increased gradually according to the stepwise development of hepatocarcinogenesis. It was higher in high-grade DNs and early HCCs than in low-grade DNs. The hepatocytes and HCC cells adjacent to peliosis and fibrous septa showed stronger VEGF expression. Angiogenesis, unpaired arteries, and sinusoidal capillarization developed from low-grade DNs and gradually increased. It was highest in HCCs. The proliferation cell nuclear antigen labeling indexes of hepatocytes and HCC cells also increased gradually as hepatocarcinogenesis progressed. Small HCCs showed a higher status of neoangiogenesis and cell proliferation activity than advanced HCCs. The degree of VEGF expression was correlated with angiogenesis and cell proliferation activity.

CONCLUSION

We conclude that VEGF plays a significant role in angiogenesis, growth, and development of HCC.

Dysplastic nodules and hepatocellular carcinoma: sensitivity of digital subtraction hepatic arteriography with whole liver explant correlation

PURPOSE

The purpose of this work was to determine the sensitivity of hepatic digital subtraction arteriography (DSA) for the detection of hepatocellular carcinoma (HCC) and dysplastic nodules (DNs) when compared with pathological findings from whole liver explants.

METHOD

Twenty-one patients 30-72 years old (mean 54 years) with cirrhosis and known or clinically suspected HCC (20 prior to chemoembolization) underwent hepatic DSA with subsequent transplantation within 80 days (mean 32 days). The prospective DSA report was compared with pathologic findings from explanted livers.

RESULTS

Overall, DSA detected 31 of 95 HCC lesions for a sensitivity of 33%. Of these 31 lesions, 28 were hypervascular and 3 were hypovascular. DSA detected all six HCCs measuring >5 cm, all six HCCs measuring 3-5 cm, and all five HCCs 2-3 cm, resulting in a sensitivity of 100% (17/17) for HCC >2 cm. DSA detected 7 of 18 HCCs measuring 1-2 cm (sensitivity 39%) and 7 of 60 HCCs < or =1 cm (sensitivity 12%). Overall sensitivity for DSA in detection of HCC < or =2 cm was 18% (14/78 lesions). None of 17 DNs (0.2-1.5 cm in size) was identified on DSA.

CONCLUSION

DSA is insensitive to small HCC (< or =2 cm), carcinomatosis arising within nodules, and DN.

Dysplastic nodules in liver cirrhosis: evaluation of hemodynamics with CT during arterial portography and CT hepatic arteriography

PURPOSE

To evaluate the portal and arterial blood supplies to dysplastic nodules in the cirrhotic liver with computed tomography (CT) during arterial portography (CTAP) and CT hepatic arteriography (CTHA).

MATERIALS AND METHODS

Nineteen histopathologically proved low-grade dysplastic nodules and 13 high-grade dysplastic nodules in 17 patients with liver cirrhosis were evaluated with CTAP and CTHA for the presence of portal and arterial blood supplies to the nodules. The nodules ranged from 0.4 to 4.5 cm in diameter (mean, 1.6 cm).

RESULTS

The portal supply was present in 14 of the 19 (74%) low-grade dysplastic nodules and in seven of the 13 (54%) high-grade dysplastic nodules. The hepatic arterial supply was increased in four of the 19 (21%) low-grade dysplastic nodules, present in nine (47%), and absent in six (32%). The arterial supply was increased in four of the 13 (31%) high-grade dysplastic nodules, present in four (31%), and absent in five (38%).

CONCLUSION

The portal and arterial supplies to the low- and high-grade dysplastic nodules were variable and inconsistent. Therefore, it is difficult to detect and characterize the dysplastic nodules on the radiologic images on the basis of the blood supply.

Proliferating cell nuclear antigen and Ki-67 labeling in hepatocellular nodules: a comparative study

AIMS/BACKGROUND

The morphologic differential diagnosis of hepatocellular nodules (HCN) is frequently difficult and objective criteria would be useful in the categorization of such lesions. This study evaluated the proliferative activity of HCN, including regenerative, macroregenerative (MRN), cirrhotic, dysplastic, and hepatocellular carcinoma (HCC), as well as intranodular cytologic changes such as bile-stained hepatocytes, eosinophilia, clear, large cell (LCC) and small cell (SCC) change, by comparing the cellular density (CD), labeling indices (LI) and density (DP) of two proliferation markers.

METHODS

Routinely processed tissue sections from 45 HCN from 17 adult liver explants were studied by immunohistochemistry for PCNA and Ki-67 (MIB-1).

RESULTS

A progressive increase in LI from regenerative to dysplastic nodules to HCC was observed with both proliferation markers. The values of the two markers were significantly correlated (p<0.001). CD, PCNA and MIB-1 LI and DP values were significantly lower in regenerative compared to dysplastic nodules or HCC. MRNs had lower PCNA and MIB-1 LI and DP than regenerative nodules, but similar CD. There were no statistically significant differences in CD, PCNA, and MIB-1 LI and DP between dysplastic nodules and HCC, comparing high versus low grade dysplasia, or HCC smaller than 2 cm with those larger than 2 cm. The CD and proliferation indices LI and DP were higher in HCC than in the surrounding non-neoplastic parenchyma. Lesions with clear cell, eosinophilic and large cell change had CD, PCNA and MIB-1 indices similar to those of regenerative nodules, while these were lower in bile-stained hepatocellular lesions (p<0.01). SCC showed CD, PCNA and MIB-1 LI and DP similar to HCC and higher than surrounding regenerative lesions (p<0.003).

CONCLUSIONS

Our results suggest that PCNA and MIB-1 values are closely correlated in HCN. Regenerative nodules are characterized by low cellular proliferation, while dysplastic nodules are usually highly proliferative lesions and may represent an early stage in hepatocarcinogenesis. Hepatocellular lesions characterized by bile stained hepatocytes, eosinophilic, clear and large cell change have low proliferation rates and may not be significant for the development of malignancy.

Areas of sinusoidal surface hepatocyte nuclear predominance in type C chronic hepatitis

AIMS/BACKGROUND

Thick hepatic plates have been considered one of the morphological characteristics of hepatocyte regeneration in cirrhotic nodules. They can be recognized by the sinusoidal surface predominance of their nuclei. We have investigated the prevalence of this in HBV and HCV infections.

METHODS AND RESULTS

This feature was more frequently present in type C chronic hepatitis with low activity of inflammation and low grade of fibrosis, than with type B chronic hepatitis. Additionally, this area of sinusoidal surface hepatocyte nuclear predominance (ASSHNP) was seen in zone II, rather than in periportal zones, in type C chronic hepatitis. Clinical data were analyzed statistically. Immunohistochemical reactivity of type IV collagen, laminin, Ulex europaeus agglutinin 1 lectin (UEA-1), and factor VIII-related antigen were increased in ASSHNP. Immunohistochemical staining of Ki-67 antigen was performed in order to assess the regenerative capacity of this area and showed a low level of regeneration. Ultrastructure of this area in type C chronic hepatitis showed a decrease in the number of mitochondria and an increase of nuclear pleomorphism together with basement membrane formation in the space of Disse.

CONCLUSION

Although the cause of these abnormalities was not clarified in this study, it is suggested that they are related to chronic hepatitis C virus (HCV) infection per se, rather than regeneration or inflammatory activity. These changes may be significant in HCV-associated hepatocarcinogenesis.

Neoangiogenesis and sinusoidal "capillarization" in dysplastic nodules of the liver

The blood supply of hepatocellular carcinoma (HCC) is primarily arterial. Recent studies reported differences of vascular, especially arterial, supply among low- and high-grade dysplastic nodules and HCC. We assessed arterialization using monoclonal antibody specific for smooth muscle actin as well as simultaneous changes in sinusoidal capillarization in cirrhotic nodules, dysplastic nodules, and HCC. We immunohistochemically stained 56 cirrhotic nodules, 20 low-grade dysplastic nodules, 27 high-grade dysplastic nodules, and 20 HCCs for alpha smooth muscle actin (to identify unpaired arteries (i.e., arteries not accompanied by bile ducts) and CD34 (indicating sinusoidal capillarization). Distribution and number of unpaired arteries and distribution of sinusoidal capillarization were graded semiquantitatively. Unpaired arteries were rare in cirrhotic nodules, significantly more common in dysplastic nodules of both types (p < 0.00001), and most common in HCC. Sinusoidal capillarization was least common in cirrhotic nodules, significantly more common in dysplastic nodules (p < 0.0035), and most common in HCC. No topographic relationship between unpaired arteries and sinusoidal capillarization was identified. These findings showed that (1) distributions of sinusoidal capillarization and unpaired arteries in dysplastic nodules are intermediate between those in cirrhotic nodules and HCC, supporting dysplastic nodules as premalignant lesions; (2) unpaired arteries are histologically useful for distinguishing dysplastic nodules from large cirrhotic nodules; and (3) areas of sinusoidal capillarization within dysplastic nodules are unrelated to location of arterialization.

Angiogenesis in hepatocellular carcinoma as evaluated by CD34 immunohistochemistry

To clarify the relationship between angiogenesis and hepatocarcinogenesis on progression of hepatocellular carcinoma (HCC), we quantitatively evaluated angiogenesis by CD34 immunohistochemistry in liver cirrhosis (LC), adenomatous hyperplasia (AH), and HCC, and proliferative activity estimated by Ki-67 immunohistochemistry. Angiogenesis was evaluated by CD34 immunohistochemistry using monoclonal antibody HPCA-2, and tumor proliferative activity was evaluated using monoclonal antibody MIB-1. We used an image analysis system to assess the microvessel density as the area percentage of the endothelial area. Angiogenesis was generally observed in HCC and there was no significant difference among all clinical stages and histological grades of HCC. On the other hand, the staining of CD34 was partly observed in sinusoids of AH, although no positive staining was seen in any sinusoids of LC. The proliferative activity was significantly correlated with the clinical stage and histological grade of HCC. Our results indicate that the quantitation of angiogenesis does not provide significant prognostic information in HCC, but that it may have diagnostic value in distinguishing HCC from non-HCC. Meanwhile, AH, which is not morphologically diagnosed as cancer, shows positive staining for CD34, suggesting that some portion of AH contains cancerous characteristics.

Prevalence of liver cell dysplasia and association with HCC in a series of 100 cirrhotic liver explants

BACKGROUND/AIMS

Liver cell dysplasia of large (LLCD) and small (SLCD) cell types may represent a premalignant change. We sought to evaluate their prevalence, relationship with the gross type of cirrhosis, aetiology of liver disease, and the presence of hepatocellular carcinoma in a series of cirrhotic livers.

METHODS

The presence and pattern of SLCD and LLCD were evaluated by careful histological analysis in 100 consecutive cirrhotic livers of viral (49%) or non viral (51%) aetiology, and with or without hepatocellular carcinoma. Prevalences were compared using Chi-square or Fisher's tests; relative risk for hepatocellular carcinoma was evaluated by the odds ratio.

RESULTS

Dysplasia was found in 82/100 of livers. Eighty-one had LLCD, with (n=49) or without (n=32) associated SLCD. SLCD alone was found in only one case. LLCD and SLCD tended to be more frequent and extensive in mixed or macronodular cirrhosis than in micronodular cirrhosis. LLCD was significantly more frequent and extensive in cirrhosis due to hepatitis B, as was SLCD in cirrhosis due to hepatitis B virus or biliary diseases, where it showed a different pattern (focal vs diffuse, respectively). LLCD and SLCD were both significantly associated with the presence of hepatocellular carcinoma, even of small size. Small foci of SLCD and widespread LLCD were the two conditions which showed the strongest association with hepatocellular carcinoma, with odds ratios of: 6.33 and 3.88, respectively. Widespread SLCD was not relevant for hepatocellular carcinoma in biliary diseases.

CONCLUSIONS

Liver cell dysplasia may be considered an additional risk factor for hepatocellular carcinoma in patients with cirrhosis and should be looked for in biopsies. Widespread LLCD and SLCD with a focal pattern are particularly relevant for hepatocellular carcinoma, whereas widespread small cell changes found in biliary diseases seem to have a different biological significance.

Clonality of large regenerative nodules in liver cirrhosis

The role of the large regenerative nodule (RN) in hepatocarcinogenesis is not clear, although the incidence of hepatocellular carcinoma (HCC) is high in cirrhotic liver. This study was aimed at clarifying the preneoplastic nature of large RN without atypia. We analyzed the clonality of HCCs and large RNs, ranging in size from 0.6 to 1.2 cm, of cirrhotic liver by X-linked human androgen receptor (HUMARA) gene assay, using the principle of random X chromosome methylation and inactivation in females. Eleven cases of HCC and five cases of large RN without atypia from ten female patients were selected. All HCCs, large RNs and paired non-tumorous tissue from adjacent liver were selectively microdissected from deparaffinized hematoxylin and eosin stained slides. Genomic DNA was isolated and digested with Hha I. Polymerase chain reaction (PCR) amplification of the HUMARA gene was performed using a PCR mixture containing [alpha-32P]-dCTP. The PCR products were separated by gel electrophoresis and analysed by autoradiography. HUMARA was informative in nine out of ten female patients. In the informative 10 HCCs from nine patients, 9 HCCs were monoclonal and one case was polyclonal. The HCC case that showed polyclonality contained many inflammatory cells in the tumor. All of the large RNs were polyclonal. No allelic loss of chromosome 18q was present in the large RNs in constrast to the 3 out of 7 HCCs, which showed allelic deletion in chromosome 18q. We conclude that all or most of the cells composing the large RNs without atypia are polyclonal and the size of a nodule may not be important in hepatocarcinogenesis. This clonality assay may be informative for the differentiation between regenerative and preneoplastic nodules in cirrhotic liver.

Aberrant dipeptidyl peptidase IV (DPP IV/CD26) expression in human hepatocellular carcinoma

BACKGROUND/AIMS

Diagnosis of small nodular lesions in the liver is often difficult because polarization of hepatocytes under pathological conditions is not as easily determined as for glandular or squamous epithelia. The aim of the present study was to investigate whether the bile canalicular enzyme dipeptidyl peptidase IV (DPP IV) would be useful to assess the pattern of hepatocellular surface polarity in liver sections.

METHODS

Expression of DPP IV activity was determined by enzymatic cytochemistry and image cytometry in 25 human hepatocellular carcinomas and five cirrhotic livers removed at transplantation. Samples from the central and/or peripheral portion of neoplastic nodules and from surrounding tissue were analyzed in each case. Control specimens were obtained from normal liver of seven patients who underwent surgery for non-neoplastic conditions.

RESULTS

In normal liver, DPP IV activity was confined to the bile canalicular plasma membrane with a zone 3 predominance in the hepatic acinus. This was also the case in the majority of pathological non-neoplastic livers, but the cell distribution pattern of DPP IV was altered in all hepatocellular carcinomas: 2/25 cases were completely devoid of DPP IV activity and in the remaining 23 DPP IV expressing hepatocellular carcinomas, three different patterns were observed that deviated distinctly from the typical canalicular pattern: (i) canaliculi were distorted and convoluted and contained an abnormally high DPP IV activity; (ii) canalicular activity was lost and enzymatic activity was restricted to isolated spots; (iii) pseudoacinar structures of hepatocytes with both basolateral and apical DPP IV expression appeared.

CONCLUSIONS

It is concluded that DPP IV is a useful bile canalicular enzyme to assess the functional polarization of hepatocytes and that aberrant DPP IV expression occurs in human hepatocellular carcinoma.

Superparamagnetic iron oxide enhanced magnetic resonance imaging of rat liver with hepatocellular carcinoma and benign hyperplastic nodule

RATIONALE AND OBJECTIVES

The authors assess the potential of a new superparamagnetic iron oxide (SPIO) in grading hepatocellular carcinoma (HCC) histologically and in differentiating HCC from benign hyperplastic nodule (HPN).

METHODS

Nine Wistar rats (with poorly to moderately differentiated HCC, well-differentiated HCC, and HPN) received drinking water containing N-nitrosomorpholine, and were examined by magnetic resonance imaging (4.7 tesla). Spin-echo images (repetition time/echo time, 600/24.5 mseconds) were obtained before and 15 minutes after intravenous administration of 10 mumol Fe/kg of SH U 555A.

RESULTS

Poorly to moderately differentiated and well-differentiated HCC showed no significant change in signal-to-noise ratio (SNR) 15 minutes after contrast, whereas HPN showed a significant decrease in SNR. The contrast-to-noise ratio (CNR) between each kind of tumor and adjacent liver parenchyma showed a significant increase at 15 minutes after contrast.

CONCLUSIONS

The SPIO discussed in this article may help to differentiate HCC from HPN, but it remains difficult to grade hepatocellular carcinoma histologically.

Stromal and blood vessel wall invasion in well-differentiated hepatocellular carcinoma

We examined hepatocellular carcinomas (HCCs) that were smaller than 2 cm in diameter. Ninety-nine nodules from 65 patients were removed for treatment. The nodules were divided into four types (A, B, C and D) according to the following criteria: first, the appearance of the margin of nodules, distinct or indistinct; and second, cellular atypia, uniform or multiple as "nodules in nodule". In 45 indistinct margin nodules, 28 showed uniform atypia (type A) and 17 were of "nodules in nodule" (type B). As for 54 distinct margin nodules, 23 were "nodules in nodule" (type C) and 31 showed uniform atypia (type D). Cancer cell invasion was divided into three types: (1) stromal invasion into fibrotic tissue and/or portal tracts, (2) blood vessel wall invasion of portal veins or hepatic veins, and (3) tumor thrombus. The stromal and vessel wall invasion occurred almost at the same rate regardless of degree of atypia. This study shows that well-differentiated HCCs in which the cancer cells show only very slight atypia have the potential for metastasis to intrahepatic and other sites.

Low proliferative activity in macroregenerative nodules: evidence for an alternate hypothesis concerning human hepatocarcinogenesis

Macroregenerative nodules are commonly thought to be hyperplastic lesions, deriving both their large size and premalignant potential from an increased proliferative rate. We have previously suggested an alternate model of macroregenerative nodule development in which neither size nor premalignant potential of macroregenerative nodules would depend on increased proliferation. We tested this hypothesis by examining the proliferative activity in macroregenerative and surrounding cirrhotic nodules.

METHODS

Eighteen macroregenerative nodules, including five type I and 13 type II, were immunostained for proliferating cell nuclear antigen (PCNA). Type II macroregenerative nodules included ten with diffuse large (7) or small (3) liver cell dysplasia only and eight containing nodule-in-nodule lesions. Five nodule-in-nodule lesions met the histologic criteria for hepatocellular carcinoma. PCNA labeling indices (PCNA-LIs; percentage positive hepatocyte nuclei/500 randomly counted cells) were determined in macroregenerative nodules and the four largest adjacent cirrhotic nodules. Nodule-in-nodule lesions were assessed separately from the background macroregenerative nodule.

RESULTS

4/5 type I and 12/13 type II macroregenerative nodules (exclusive of NIN lesions) had PCNA-LIs lower than the mean of surrounding cirrhotic nodules. All nodule-in-nodule lesions, whether atypical or overtly malignant, had PCNA-LIs greater than any surrounding nodules. In conclusion, macroregenerative nodules have PCNA-LIs indistinguishable from, and often lower than, surrounding cirrhotic nodules. Increased proliferative activity only occurs with the development of atypia and transition to hepatocellular carcinoma.

CONCLUSION

Macroregenerative nodules derive neither their size nor their premalignant potential from on-going rapid proliferation, a finding consistent with our alternate hypothesis of macroregenerative nodule development.

Non-neoplastic nodular lesions in the liver

The classical nomenclature and categorization of neoplastic and non-neoplastic nodular lesions of the liver are being revised due to the tremendous volume of information recently published on this issue. The diagnostic histopathology of non-neoplastic nodular (tumor-like) lesions of the liver that are recognizable in biopsied, surgically resected and autopsied livers is reviewed using current terminology. Generally, such nodules are infrequent and even rare in routine liver specimens. Non-neoplastic nodules include focal nodular hyperplasia, nodular regenerative hyperplasia, compensatory hyperplasia of the liver, pseudonodule of the liver demonstrable by angiography, partial nodular transformation, focal fatty change, nodular hepatic area shown by modified angiography, cirrhotic large regenerative nodule with variable atypia, anoxic pseudolobular necrosis, intrahepatic bile duct adenoma, biliary and mesenchymal hamartoma, and mesenchymal nodular lesions such as inflammatory pseudotumor and pseudolymphoma, pseudolipoma, peliosis hepatis, solitary necrotic nodule, and so on. Some of these develop preferentially in non-cirrhotic or cirrhotic livers, while others occur with similar prevalence in cirrhotic and non-cirrhotic livers. Some occur multiply or diffusely and others singly. As to the pathogenesis of these nodules, it is speculated that hyperplasia due to disturbed intrahepatic circulation or hormonal imbalance, preneoplastic characteristics, abnormal metabolic disturbance, hamartoma or focal necrobiotic processes, and infection have a role. Knowledge and awareness of these non-neoplastic nodular lesions are necessary for precise diagnosis and differentiation of these nodular lesions from neoplastic hepatic nodules.