Pathology of hepatocellular carcinoma: recent update]

In recent years, growing number of literatures have supported the concept that large nodules usually found in cirrhotic livers represent premalignant lesions in the setting of chronic liver disease. With the use of advanced imaging techniques, nodules suspicious for malignancy have often been identified and resected. While some resected lesions were found to be small hepatocellular carcinomas (HCCs), others were not. Some of these non-malignant nodules were devoid of atypia, some had architectural or cytological atypia insufficient for a diagnosis of HCC though they are suggestive of a premalignant state, while others contained microscopic subnodules of HCC. In follow-up studies and series of explants from liver transplant centers, the occasional finding of microscopic foci of HCC in the nodules was confirmed and significant associations with HCC elsewhere in the same liver were established. Such findings suggested that these nodular lesions, which are referred as "dysplastic nodules" (or adenomatous hyperplasia), are probably a frequent pathway in human hepatocarcinogenesis. We discuss the pathological characteristics of dysplastic nodules and small HCCs.     

Preneoplastic lesions in human hepatocarcinogenesis.

The early stages of hepatocarcinogenesis in human chronic liver diseases are characterized by the emergence of preneoplastic lesions of which some will eventually develop into hepatocellular carcinoma (HCC). Basic studies on the genetic and epigenetic alterations of these preneoplastic lesions may eventually lead to new therapeutic strategies. Clinicopathological studies are also important in order to determine optimal management of patients with a preneoplastic lesion. This article aims to provide a comprehensive review of the current concepts of preneoplastic lesion in chronic liver diseases. The microscopical small-cell dysplastic focus is the smallest morphologically recognizable precursor lesion of HCC and therefore is a logical target of study to elucidate the earliest events in hepatocarcinogenesis. In contrast, large-cell dysplasia is not a precursor lesion, but appears to be of clinical value because of its good predictive value for development of HCC. Dysplastic nodules (DNs) are macroscopically recognizable precursor lesions of HCC and high-grade DNs (HGDNs) have a risk of malignant transformation. Detection of DNs and correct differentiation from small HCC (<2 cm) is sometimes difficult, especially when only imaging techniques are used. Additional clinicopathological studies on identification and optimal treatment of DNs are necessary. Molecular studies on HGDNs and small HCCs may yield much information on the genetic mechanisms involved in the transition from severe dysplasia to early malignancy. In contrast, currently available data indicate that (large) regenerative nodules do not represent a distinct step in hepatocarcinogenesis. Animal models will be helpful in the further unravelling of human HCC development, provided that studies are performed on models that are good representatives of human hepatocarcinogenesis. We propose three criteria by which good mimickers can be identified.     

Genomic heterogeneity in synchronous hepatocellular carcinomas

BACKGROUND: Hepatocellular carcinoma (HCC) arising in cirrhosis is frequently multifocal. Whether HCC develops monoclonally or multiclonally is an unresolved question. Of the multiple tumour nodules present in many patients, it has not been established whether the smaller lesions represent intrahepatic metastases or de novo cancers. AIMS: To assess the degree of genomic heterogeneity in synchronous HCCs in cirrhosis. METHODS: The arbitrarily primed polymerase chain reaction technique was utilised to compare the DNA fingerprint of HCCs and regenerative nodules (RNs) removed from cirrhotic explant livers. RESULTS: Polymorphic genomic heterogeneity was noted in 54 HCCs and 31 RNs microdissected. Even satellite nodules in close proximity within the same segment of the liver were found to have distinct genomic patterns. CONCLUSION: Such genomic heterogeneity in synchronous HCCs may explain poor patient survival after surgical resection. If the smaller tumours are de novo lesions rather than metastases (as these data suggest), then current concepts regarding liver resection as a curative treatment modality for HCC may require reassessment.     

Chromosomal allelic imbalance evolving from liver cirrhosis to hepatocellular carcinoma

BACKGROUND & AIMS: Cirrhotic nodules have long been assumed to be the precancerous lesions of hepatocellular carcinoma (HCC). We thus investigated the allelic imbalance (AI) in cirrhotic nodules to define the genetic aberrations in early hepatocarcinogenesis. METHODS: One hundred eighty cirrhotic nodules from 7 female patients with HCC were collected by microdissection. Their clonality nature was assessed by examining the X chromosome methylation pattern. AI in monoclonal cirrhotic nodules and the corresponding HCCs were analyzed with microsatellite polymorphic markers. RESULTS: One hundred one out of 180 nodules (56.1%) were monoclonal and the average fractional AI (FAI) was 21%, lower than the 40% in HCC. Their overall AI patterns differed significantly from that in HCC (P < 0.001) with FAI on 2q, 4q, 8p, and Xq higher than the mean value. Comparison of FAI in nodules (stratified by increasing total AI events) further revealed a progressive increase of FAI on 4q, 8p, and Xq. In contrast, FAI on 1p, 13q, 16q, and 17p were low in nodules but rose above the mean only in HCC. CONCLUSIONS: About half of the cirrhotic nodules are monoclonal and already have chromosome aberrations. AI on 4q, 8p, and Xq may be the earlier mutations, whereas AI on 1p, 13q, 16q, and 17p occurs late in hepatocarcinogenesis.     

Early hepatocellular carcinoma and dysplastic nodules

It has been established that small, equivocal nodular lesions such as dysplastic nodules (DNs) and small well-differentiated hepatocellular carcinomas (early HCCs) are frequently observed in noncancerous liver tissues resected along with HCCs and in explant cirrhotic livers. DNs are classified into low-grade DNs or high-grade DNs on the basis of cytological and architectural atypia; high-grade DNs show varying degrees of cytological or architectural atypia, or both. Early HCCs are indistinctly nodular and highly differentiated and are frequently difficult to differentiate from high-grade DNs. Although the pathological diagnosis of high-grade DNs and early HCCs is controversial, the presence of tumor cell invasion into the intratumoral portal tracts (stromal invasion) is a helpful clue for differentiating early HCC from high-grade DNs. It is highly suggested that many HCCs occurring in cirrhotic liver arise in DNs and develop to classical HCC in a multistep fashion.     

Failure to detect genetic alteration of the mannose-6-phosphate/insulin-like growth factor 2 receptor (M6P/IGF2R) gene in hepatocellular carcinomas in Japan.

The mannose-6-phosphate/insulin-like growth factor 2 receptor (M6P/IGF2R) suppresses cell growth through binding to the insulin-like growth factor 2 (IGF2) and latent complex of the transforming growth factor-beta (TGF-beta). Recently, it was reported in the United States that loss of heterozygosity (LOH) and mutations in exons 27, 28, and 31 of the M6P/IGF2R gene are frequent in hepatocellular carcinomas (HCCs) and adenomas. In view of the possible importance of this finding, especially for differential diagnosis of small hepatic lesions, we analyzed 43 primary HCCs, 2 adenomatous hyperplasias (AHs), and 3 regenerative nodules (RNs) developing in 42 Japanese patients in Japan for LOH using the polymorphic locus and for mutations by both single strand conformation polymorphism (SSCP) and direct sequencing methods. In the LOH study, 21 out of 22 informative HCCs and all of the informative AHs and RNs showed no allelic loss. In mutational studies of exons 27, 28, and 31, no mutations were detected either by SSCP or direct sequencing analysis in any of the 48 lesions. Thus inactivation of the M6P/IGF2R gene because of genetic alteration does not appear to be essential for hepatocarcinogenesis in Japan.     

Comprehensive analysis of genetic aberrations linked to tumorigenesis in regenerative nodules of liver cirrhosis

Journal of Gastroenterology - Hepatocellular carcinoma (HCC) recurrently develops in cirrhotic liver containing a number of regenerative nodules (RNs). However, the biological tumorigenic potential...     

MR with Gd-EOB-DTPA in assessment of liver nodules in cirrhotic patients

To date the imaging diagnosis of liver lesions is based mainly on the identification of vascular features, which are typical of overt hepatocellular carcinoma(HCC), but the hepatocarcinogenesis is a complex and multistep event during which, a spectrum of nodules develop within the liver parenchyma, including benign small and large regenerative nodule(RN), low-grade dysplastic nodule(LGDN), high-grade dysplastic nodule(HGDN), early HCC, and well differentiated HCC. These nodules may be characterised not only on the basis of their respective different blood supplies, but also on their different hepatocyte function. Recently, in liver imaging the introduction of hepatobiliary magnetic resonance imaging contrast agent offered the clinicians the possibility to obtain, at once, information not only related to the vascular changes of liver nodules but also information on hepatocyte function. For this reasons this new approach becomes the most relevant diagnostic clue for differentiating low-risk nodules(LGDN-RN) from highrisk nodules(HGDN/early HCC or overt HCC) and consequently new diagnostic algorithms for HCC have been proposed. The use of hepatobiliary contrast agents is constantly increasing and gradually changing the standard of diagnosis of HCC. The main purpose of this review is to underline the added value of Gd-EOB-DTPA in early-stage diagnoses of HCC. We also analyse the guidelines for the diagnosis and management of HCC, the key concepts of HCC development, growth and spread and the imaging appearance of precursor nodules that eventually may transform into overt HCC.     

肝细胞癌癌前结节影像学特征的研究进展

肝细胞癌(HCC)发生是一个多步骤过程,在其发展中检测出HCC癌前病变和进展期HCC,对预测肿瘤行为、判断病变程度、采用最佳治疗策略、改善患者生存至关重要。肝脏成像技术的快速进展和广泛应用,尤其是肝细胞特异性对比剂钆塞酸二钠MRI(Gd-EOB-DTPA MRI)可提供肝结节血管变化、肝细胞功能信息,能够精确区分肝硬化再生结节、低度异型增生结节、高度异型增生结节、早期HCC(early HCC)和HCC,从而进行恶性进展的风险度分层。现综述Gd-EOB-DTPA MRI在HCC早期诊断中的价值,分析HCC多步发展过程中的关键概念,以及癌前病变最终可能转化成典型HCC的影像学表现。     

磁共振磁敏感加权成像在肝硬化结节多步癌变中的临床应用

肝癌早期发现,早期治疗,明显提高5年生存率。肝硬化患者,绝大部分均经历肝硬化结节多步癌变的过程,即由再生结节发展为异型增生结节,其中高分化异型增生结节发展为癌变结节后（早期肝癌）,再发展为小肝癌,小肝癌最后发展成进展期或晚期肝癌。上述结节的一系列变化过程中,其结节内内源性铁逐步廓清,本文重点介绍利用磁共振磁敏感加权成像（SWI）技术观察结节中内源性铁变化情况,同时结合常规MRT2W1、弥散加权成像（DWI）和动态增强等技术,提高识别肝硬化背景下的癌变／早期肝癌结节能力,从而对进一步提高早期小肝癌的诊疗,具有更重要的临床意义。     

Macroregenerative nodules in a series of adult cirrhotic liver explants: Issues of classification and nomenclature

Macroregenerative nodules (MRNs), probably representing a pathway for human hepatocarcinogenesis, are generally classified into type I MRNs (or ordinary adenomatous hyperplasia) and type II MRNs (or atypical adenomatous hyperplasia), on the basis of imprecise definitions of cytological and architectural atypia. It is currently believed that type II MRNs are probably true precursors of hepatocellular carcinoma (HCC), whereas type I lesions may simply represent large regenerative nodules. A series of 155 consecutive adult cirrhotic liver explants were examined for evidence of MRNs, HCC, and liver cell dysplasia (LCD) of large and small cell types, and their appearance, in terms of proposed classification schemes, was reviewed. There was evidence indicating that the presence of either type of MRN was associated with an increased incidence of HCC (all MRNs, P < .00019; type I MRNs, P < .067; type II MRNs, P < .012) compared with cirrhotic livers without MRNs. A subset of younger patients with a large (uncountable) number of MRNs in their livers, who did not show any increased incidence of carcinoma, was identified. Excluding these cases from statistical analysis, all associations were strengthened, implying either that malignant progression had not had time to occur in this younger population or that these nodules were simply large regenerative nodules without malignant potential. MRNs from these livers were histologically indistinguishable from MRNs occurring in more limited numbers, although atypical changes other than large cell type LCD were less frequent. No independent association between LCD of large cell type and HCC was found in the entire series. Deleting this feature from the criteria for cytological atypia resulted in a stronger association of both types of MRNs with HCC (redefined type II MRNs/HCC, P < .0001; redefined type I MRNs/HCC, P < .0306). Some of the type II MRNs remaining after exclusion of large cell type LCD showed “borderline” changes insufficient for a diagnosis of HCC, but most type II MRNs (82%) contained expansile “nodule-in-nodule” growth patterns. The conclusions of this report are that (1) histological examination of type I MRNs is insufficient in many cases to distinguish large regenerative nodules from neoplastic ones; (2) LCD of large cell type should not be used as a criterion for terming an MRN atypical; and (3) expansile “nodule-in-nodule” formation in MRNs should be considered to represent evidence of architectural atypia.     

Imaging diagnosis of hepatocellular carcinoma]

In patients with chronic liver disease, hepatocellular carcinomas are developed from regenerative nodule via dysplastic nodule and early hepatocellular carcinoma to advanced hepatocellular carcinoma during multistep hepatocarcinogenesis. In this article, imaging findings of various imaging modalities are described pertaining to the above mentioned hepatocellular nodules occurring in the cirrhotic liver, correlating with pathologic findings.     

Multistep hepatocarcinogenesis from a dysplastic nodule to well-differentiated hepatocellular carcinoma in a patient with alcohol-related liver cirrhosis

We describe a rare case of the transformation of a dysplastic nodule into well-differentiated hepato- cellular carcinoma (HCC) in a 56-year-old man with alcoholrelated liver cirrhosis. Ultrasound (US) disclosed a 10 mm hypoechoic nodule and contrast enhanced US revealed a hypovascular nodule, both in segment seven. US-guided biopsy revealed a high-grade dysplastic nodule characterized by enhanced cellularity with a high N/C ratio, increased cytoplasmic eosinophilia, and slight cell atypia. One year later, the US pattern of the nodule changed from hypoechoic to hyperechoic without any change in size or hypovascularity. US-guided biopsy revealed well-differentiated HCC of the same features as shown in the first biopsy, but with additional pseudoglandular formation and moderate cell atypia. Moreover, immunohistochemical staining of cyclase- associated protein 2, a new molecular marker of well- differentiated HCC, turned positive. This is the first case of multistep hepatocarcinogenesis from a dysplastic nodule to well-differentiated HCC within one year in alcohol-related liver cirrhosis.     

Emergence of malignant lesions within an adenomatous hyperplastic nodule in a cirrhotic liver. Observations in five cases

Five cases of an adenomatous hyperplastic nodule or a similar lesion resected from a cirrhotic liver in which early malignant foci were seen as small nodule-in-nodule lesions are described. These hyperplastic lesions were detected by imaging diagnosis in patients with nonalcoholic cirrhosis, mostly during routine clinical follow-up. In 2 patients, recurrence of hepatocellular carcinoma occurred 11 mo and 15 mo postresection. Thus, these nodule-in-nodule lesions in an adenomatous hyperplastic nodule seem to represent an early stage of hepatocarcinogenesis in humans. In nonalcoholic cirrhotic patients from Japan and Southeast Asia, in whom hepatocellular carcinoma is endemic, an adenomatous hyperplastic nodule or a similar hyperplastic lesion that occurs in cirrhotic livers may be preneoplastic and already committed to malignant transformation.     

NORE1B, a candidate tumor suppressor, is epigenetically silenced in human hepatocellular carcinoma

BACKGROUND/AIMS: In human hepatocellular carcinoma (HCC) the ras-proto-oncogene is rarely mutated. We therefore studied the possible inactivation of the putative tumor-suppressors and ras-associating proteins, NORE1A, NORE1B, and RASSF1A in HCCs by mutation or epigenetic gene silencing through promoter-CpG hypermethylation. METHODS: SSCP-analyses, sequencing, and methylation-specific PCR were performed in 28 fibrotic/cirrhotic livers and 40 HCCs. RESULTS: The sequence of NORE1A/B exhibited no deviations and that of the RASSF1A gene a non-silent polymorphism ( approximately 10% of cases) and a missense mutation (one HCC). Both alterations may affect the growth-inhibiting capability of RASSF1A. Epigenetic inactivation of NORE1B was found in 62% of the HCCs and in hepatocarcinoma-cell lines due to considerable promoter-methylation of the gene. Methylation was detected also for RASSF1A in HCCs and hepatocarcinoma cell-lines. As a result, 97% of the HCCs revealed epigenetic silencing of NORE1B, RASSF1A, or both. In contrast every third fibrotic/cirrhotic liver only exhibited silencing of one or both genes. CONCLUSIONS: The candidate tumor suppressor genes NORE1B and RASSF1A are epigenetically down-regulated alone in at least 62%, or in combination in 97% of the HCCs studied. This indicates a frequent and critical event in hepatocarcinogenesis, which may allow HCCs to subverse growth-control in the presence of an unaltered Ras.     

Frequent loss in chromosome 8p loci in liver cirrhosis accompanying hepatocellular carcinoma

Most hepatocellular carcinoma (HCC) is preceded by liver cirrhosis, but the genetic changes involved in cirrhosis are not well understood. We therefore studied loss of heterozygosity (LOH) in cirrhotic and neoplastic foci in livers of 14 patients with HCC. The samples, microdissected from paraffin-embedded tissues, were analyzed using a polymerase-chain-reaction-based assay for dinucleotide repeat polymorphisms on 8p. Of the 14 cases, 13 showed constitutional heterozygosity for the microsatellite markers. In 7 (54%) of these 13 informative cases, LOH was detected in the primary HCC and, in these 7 doubly informative (informative and LOH-positive in primary HCC) cases, LOH was found in 16 (70%) of 23 liver cirrhotic foci. The pattern of 8p allelic loss was identical in each doubly informative tumor; however, some of the liver cirrhotic foci harbored an 8p loss identical to that seen in the primary HCC, some harbored a different 8p loss, and some did not harbor any 8p loss. The remaining 6 cases without LOH on 8p in HCC showed no 8p loss in any cirrhotic foci. Presumably HCC could develop from cirrhotic cells harboring 8p loss.Abbreviations HCC hepatocellular carcinoma - LOH loss of heterozygosity - PCR polymerase chain reaction - AH adenomatous hyperplasia - AAH atypical adenomatous hyperplasia     

The vascular profile of regenerative and dysplastic nodules of the cirrhotic liver: implications for diagnosis and classification.

We investigated the angiogenic phenotype of regenerative and dysplastic hepatocellular nodules to assess whether these lesions have distinct vascular profiles compared with the adjacent nonneoplastic or malignant liver. Forty-three liver nodules surgically removed from 18 patients were classified into regenerative and dysplastic categories. Serial sections of each nodule, adjacent cirrhotic liver (16 patients), and associated hepatocellular carcinoma (HCC) (6 patients), have been immunostained against CD31 and alpha-smooth muscle actin (alphaSMA) to detect capillary and muscular vessels. The study included 20 large regenerative nodules (LRNs), 13 low-grade dysplastic nodules (LGDNs), and 10 high-grade dysplastic nodules (HGDNs). The number of both capillary units and unpaired arteries was significantly increased in HGDNs and malignant lesions over LGDNs, regenerative, and cirrhotic nodules (P <.01), which showed an overlapping vascular profile. In addition, the number of capillary units, but not that of unpaired arteries, was significantly increased in HCC compared with HGDNs (P <.01). These results show that certain angiogenic features segregate HGDNs from other nonmalignant nodules such as LRNs and LGDNs. The former group of lesions is similar to HCC whereas the latter group is undistinguishable from the adjacent cirrhosis as far as their vascular profile is concerned. The adopted investigative approach does not support the morphological distinction between LRNs and LGDNs although it suggests that HGDNs are likely advanced precursors of HCC. An abnormal number of capillary units and/or unpaired arteries in a nonmalignant hepatocellular nodule can be diagnostically helpful to identify a precancerous lesion.     

Evidence for a polyclonal nature of the cell infiltrate in sinus histiocytosis with massive lymphadenopathy (Rosai-Dorfman disease)

Summary. Sinus histiocytosis with massive lymphadenopathy (SHML), or Rosai-Dorfman disease, is rare histiocytic disorder of known origin which shares several cell markers with Langerhans'cell histiocytosis (LCH). Although Rosai-Dorfman cells exhibit an aberrant immunophenotype, the indolent clinical course of SHML suggests a reactive disorder rather than a neoplastic process. Until recently this was prevailing opinion concerning LCH also, but recent studies have detected clonal histiocytes in all forms of this latter condition, which is therefore considered a clonal neoplastic disorder with highly variable biologial behaviour. To determine whether the histiocytic proliferation in SHML is polyclonal or clonal we used X-linked polymorphic loci to assess clonality in lesional tissues in two women. Polymorpic regions of the human androgen receptor (HUMARA) locus were amplified by polymerase chain reaction (PCR) analysis. The HUMARA locus was informative in both cases and, following digestion with methylation-sensitive enzymes, typical polyclonal X-inactivation patterns were observed. Since abnormal cells accounted for >90% lesional tissue cells, we conclude that Rosai-Dorfman histiocytic proliferation was polyclonal in the women studied.