Vascularization of small hepatocellular carcinomas: correlation with differentiation

Abstract: Background: Hepatocellular carcinoma (HCC) is generally considered a hypervascular tumor when visualized by angiography. However, small HCCs are not always found to be hypervascular. Methods: To evaluate this, 50 HCCs ≤ 3 cm in diameter were studied. The 50 tumors consisted of 16 well-differentiated HCCs, 25 moderately differentiated HCCs, and 9 that were each a mixture of well- and moderately differentiated HCC. Results: The mean number of portal tracts in the well-differentiated HCCs was 34% of the number in the surrounding nontumorous liver, and few intratumoral arterioles were seen. In contrast, the mean number of portal tracts in the moderately differentiated HCCs was 0.6% of the number in the surrounding nontumorous liver, and abundant intratumoral arterioles were seen. For HCCs that contained both well-differentiated and moderately differentiated tumor, the distribution of portal tracts and intratumoral arterioles in each portion was similar to that seen in well-differentiated or moderately differentiated HCC alone, respectively. HCCs that were larger than 1.5 cm in diameter had fewer portal tracts and more intratumoral arterioles than HCCs whose diameters were ≤ 1.5 cm. Conclusions: As small HCCs increase in size and become increasingly dedifferentiated, the number of portal tracts apparently decreases and intratumoral arterioles develop. These findings may reflect changes in the hemodynamics as the HCC develops.     

Pathomorphologic study on early hepatocellular carcinoma (HCC)--a study of cell density in well-differentiated HCC of the early stage

In order to clarify the histologic characteristics of well-differentiated hepatocellular carcinoma (HCC), a comparative morphometric study on cell density was performed in 15 HCCs smaller than 2 cm in diameter, 6 HCCs with marked fatty and/or clear cell change, 7 hyperplastic nodules, 5 hyperplastic nodules containing foci of HCC, and non-cancerous areas of the livers bearing small HCC. In well-differentiated HCC, marked increase of cell density accompanying by decrease of cell size and increase of nuclear cytoplasm ratio were prominent, and the cell density was approximately two times larger than that of the non-cancerous area in most cases. In HCCs with marked fatty and/or clear cell change, as an increase of cell density was not evident because of swelling of the cytoplasm due to fat and/or glycogen accumulation, it should be careful to differentiate them from non-cancerous nodular lesions including hyperplastic nodule with marked fatty change. Hyperplastic nodules could be divided into two groups; those with marked increase of cell density, and those without increase of cell density. In the former group, 5 of the 7 nodules contained cancerous foci.     

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.     

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

Abstract: 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.     

Tumor hemodynamics in hepatic nodules associated with liver cirrhosis: relationship between cancer progression and tumor hemodynamic change]

Tumor hemodynamics including arterial vascularity (AV) and portal perfusion (PP) were evaluated in histologically confirmed 55 hepatic nodules associated with cirrhosis using ultrasonographic (US) angiography during intraarterial carbon dioxide microbubbles injection and CT during arterial portography. Tumor hemodynamic patterns were classified into 6 types as follows: Type I (n = 10): PP (+), AV (hypo); Type I' (n = 2): PP (+), AV (iso); Type II (n = 5): PP (-), AV (hypo); Type III (n = 8): PP (-), AV (iso); Type IV (n = 25): PP (-), AV (hyper), Type V (n = 5): PP (partially +), AV (vascular spot in hypovascular). Eight nodules of Type I were diagnosed as benign nodules histologically including adenomatous hyperplasia (AH) (n = 6) and regenerative nodule (n = 2). Hundred percent (5/5) of Type II and 88% (7/8) of Type III nodules were well-differentiated HCC, in contrast to 8% (2/25) of Type IV nodules, typical HCCs. Fatty metamorphosis was observed in 75% (6/8) of Type III nodules, in contrast to 16% (4/25) of typical (classical) HCC nodules (Type IV). We concluded that at the malignant transformation from AH to HCC, reduction of portal blood flow in the nodule precedes the initiation of the increase of the arterial tumor vessel. Moreover, early stage HCC could exhibit hypovascular (Type I, II), isovascular (Type III), or vascular spot in hypovascular pattern (Type V) compared with a typical HCC (Type IV). It was also suggested that the more mature as a neoplasms the HCC becomes, the more the arterial tumor vessel in the nodule increases and fatty metamorphosis of well-differentiated HCC is highly related with tumor hemodynamic condition, i.e., hypoperfusion state from both arterial and portal vessel.     

Assessment of tumor hemodynamics in small hepatocellular carcinoma: comparison of Doppler ultrasonography, angiography-assisted computed tomography, and pathological findings.

AIM: We evaluated the usefulness of Doppler ultrasonography (DUS) for the analysis of tumor hemodynamics in small hepatocellular carcinoma (HCC). METHODS: We compared Doppler ultrasound (DUS) findings with angiography-assisted computed tomography (Angio-CT) such as CT during arterial portography and during hepatic arteriography in the evaluation of the intratumoral hemodynamics, and with pathologic findings in 45 small HCC nodules (< or =3.0 cm in diameter) of 43 patients. DUS flow pattern of each nodule was categorized into three types: afferent continuous flow (Type 1), afferent pulsatile flow with afferent continuous flow (Type 2), and afferent pulsatile flow without afferent continuous flow (Type 3). Intratumoral blood supply was determined by Angio-CT, and pathologic findings were evaluated on resected or biopsied specimen. RESULTS: Based on Angio-CT findings, Type 1 nodules showed decreased arterial blood supply (ABS) without decreased portal blood supply (PBS). Type 2 nodules showed unchanged ABS but decreased PBS. Type 3 nodules showed both increased ABS and decreased PBS. DUS findings well represented blood supply of HCC evaluated by Angio-CT. In addition, all Type 1 and 2 nodules were well-differentiated HCC, and all Type 3 nodules were moderately or poorly differentiated HCC; DUS findings well reflected differentiation of HCC. CONCLUSIONS: DUS is a non-invasive imaging method and can be used for the evaluation of the stage of malignancy of small HCC.     

Observation of microvascular casts of human hepatocellular carcinoma by scanning electron microscopy

The microcirculation of hepatocellular carcinomas (HCCs) and surrounding tissue was observed three-dimensionally by scanning electron microscopy of vascular casts made from 10 livers at autopsy. The livers were perfusion-washed and cast with resin through both the hepatic artery and portal vein branches. The HCCs observed ranged from several millimeters to 3 cm in size. A vascular plexus proliferated around the HCC nodules in all cases. Both portal vein and hepatic artery branches proliferated markedly to form the plexus in 5 patients. These vessels communicated directly with the blood sinuses of the HCCs as feeder vessels. HCC cells replaced normal cells while maintaining the liver’s trabecular structure in 2 cases. At the borders of these HCCs, there was direct communication between the hepatic sinusoids and the tumor blood sinuses. Efferent vessels of the tumors were generally difficult to identify but vessels resembling hepatic vein branches were detected in one 4-mm HCC nodule after microdissection. Thus, HCC was demonstrated to be supplied not only by the hepatic artery but also by the portal vein and hepatic sinusoids. This may be one of the reasons why cancer cells survive in the tumor margins and daughter nodules after transcatheter arterial embolization of HCC.     

Observation of microvascular casts of human hepatocellular carcinoma by scanning electron microscopy.

The microcirculation of hepatocellular carcinomas (HCCs) and surrounding tissue was observed three-dimensionally by scanning electron microscopy of vascular casts made from 10 livers at autopsy. The livers were perfusion-washed and cast with resin through both the hepatic artery and portal vein branches. The HCCs observed ranged from several millimeters to 3 cm in size. A vascular plexus proliferated around the HCC nodules in all cases. Both portal vein and hepatic artery branches proliferated markedly to form the plexus in 5 patients. These vessels communicated directly with the blood sinuses of the HCCs as feeder vessels. HCC cells replaced normal cells while maintaining the liver's trabecular structure in 2 cases. At the borders of these HCCs, there was direct communication between the hepatic sinusoids and the tumor blood sinuses. Efferent vessels of the tumors were generally difficult to identify but vessels resembling hepatic vein branches were detected in one 4-mm HCC nodule after microdissection. Thus, HCC was demonstrated to be supplied not only by the hepatic artery but also by the portal vein and hepatic sinusoids. This may be one of the reasons why cancer cells survive in the tumor margins and daughter nodules after transcatheter arterial embolization of HCC.     

Surgical treatment of hepatocellular carcinoma

Surgery for hepatocellular carcinoma (HCC) includes partial liver resection (LR) and liver transplantation (LT). Although LT represents the most efficient treatment in patients with small HCC, <30% of patients are eligible for LT because of restrictive criteria (one nodule <5 cm or two to three nodules <3 cm without macroscopic vascular invasion), graft unavailability and the high cost of the procedure. For large HCC, LR remains the only potential curative treatment. LR is now safer, with a low rate of mortality. Selective preoperative morphological assessment, preoperative use of portal vein embolization for increasing future remnant liver volume and the improvement of surgical techniques such as the use of intermittent clamping and anterior approach are factors that improve the safety and tolerance of LR. In patients with small HCCs and a preserved liver function (Child-Pugh grade A), good long-term survival can be achieved after anatomical resection that removes the tumor(s) and its portal vein territory. These good results of LR for small HCC and the increasing duration of the waiting list for candidates of LT have renewed the place of LR as a bridge treatment before LT.     

Immunohistologic study on the expressions of alpha-fetoprotein and protein induced by vitamin K absence or antagonist II in surgically resected small hepatocellular carcinoma.

Sixty-eight cases of single hepatocellular carcinoma (HCC) with less than 3 cm of diameter were immunohistochemically examined for the expressions of alpha-fetoprotein (AFP) and protein induced by vitamin K absence or antagonist II (PIVKA-II). In cancerous tissues, the expression rate was significantly higher for PIVKA-II (34 cases [50%]) than AFP (21 cases [31%]) (P <.05), suggesting a higher specificity of PIVKA-II to small HCC. Sixteen of the 68 cases (24%) were positive to both AFP and PIVKA-II, and in 8 of the 16 cases, AFP and PIVKA-II expressing areas within a nodule were clearly divided by a fibrous septum. According to histologic grades, PIVKA-II expression was confirmed in 2 of the 15 well-differentiated HCCs, and in the well-differentiated component of 6 of the 12 "nodule-in-nodule"-type well-differentiated HCCs. AFP expression was not found in well-differentiated HCCs, but found in 16 of the 40 moderately differentiated HCCs (40%) and in the moderately differentiated component of 3 of the 12 "nodule-in-nodule"-type well-differentiated HCCs. The positive rate in the tissues was correlated to the serum levels for both AFP and PIVKA-II. In addition, frequency of tissue-PIVKA-II expression was higher than tissue-AFP expression in the cases whose serum protein level was within the normal range. This indicates that AFP and PIVKA-II have different patterns of tissue expression and of secretion to the blood. In comparison with tissue-AFP-negative cases, tissue-AFP-positive HCCs had a larger tumor size, higher frequencies of portal vein invasion and intrahepatic metastasis, a high Ki-67 labeling index, and a lower rate of recurrence-free survival. Thus, tissue-AFP-positive HCCs are suggested to be biologically more malignant than those HCCs that are AFP-negative and PIVKA-II-positive.     

Small hyperechoic nodules in chronic liver diseases include hepatocellular carcinomas with low cyclin D1 and Ki-67 expression.

In spite of the importance of periodic screening for hepatocellular carcinoma (HCC) by ultrasonography (US) in patients with underlying liver disease, the clinicopathological characteristics of hyperechoic nodules have not been clearly evaluated. The aim of this study was to characterize the pathological and proliferating features of small hyperechoic nodules. Tissue specimens of 55 hyperechoic and 107 hypoechoic nodules less than 20 mm in diameter in patients with chronic liver disease were obtained by echo-guided needle biopsy and examined histopathologically. Of these, 42 (76%) hyperechoic and 56 (52%) hypoechoic nodules were diagnosed as HCC, and 82% of hyperechoic HCCs contained fatty change and/or clear cell change. In addition, immunohistochemical staining using cyclin D1, p53, and Ki-67 was examined. A high-level expression of cyclin D1 was found in only 5% of hyperechoic HCCs, in contrast to 38% of hypoechoic HCCs (P <.02). The labeling index of Ki-67 in hyperechoic HCCs was lower than in hypoechoic HCCs (4.2% vs. 8.9%; P <.003). However, there was no difference on p53 staining between them. Retrospective follow-up study revealed that hyperechoic nodules showed slow growth (doubling time, median: 1,403 days) initially, and came to show rapid growth (doubling time, median: 56 days). From these results, small hyperechoic nodules in chronic liver diseases are worth notice as candidates for well-differentiated HCC with low cyclin D1 and Ki-67 expression.     

Small hepatic nodules (< or =2 cm) in cirrhosis patients: characterization with contrast-enhanced ultrasonography.

AIM: We evaluated the efficacy of contrast-enhanced ultrasonography (CEUS) for the characterization of small hepatic nodules (< or =2 cm) in cirrhosis patients. PATIENTS AND METHODS: Thirty cirrhosis patients with 30 hepatic nodules (1-2 cm) were enrolled in this study. Eighteen hepatic nodules were hepatocellular carcinomas (HCC) and 12 were benign lesions. CEUS was performed using microbubble contrast (Levovist). With surrounding hepatic parenchyma as a reference, two characteristics of hepatic nodules, including arterial phase enhancement (AE) and the absence of delayed phase enhancement (ADE), were evaluated as criteria for the diagnosis of HCC. A radiologist independently reviewed the dynamic computed tomographies (CT) of 26 hepatic nodules. RESULTS: CEUS showed AE in 15 nodules (13 HCC and two benign) and ADE in 17 lesions (14 HCC and three benign). For HCC, the coincidental AE of both CEUS and dynamic CT was 40%. Using both AE and ADE for HCC diagnosis, the sensitivity, specificity, accuracy, positive predictive value and negative predictive values were 55.6%, 91.7%, 70%, 90.9% and 57.9%, respectively. When using either AE or ADE for HCC diagnosis, the same parameters were 94.4%, 66.7%, 83.3%, 81% and 88.9%, respectively. One benign hepatic nodule with both AE and ADE was diagnosed as HCC 29 months after the CEUS study. CONCLUSIONS: A combination of characteristics of AE and ADE as determined by CEUS was highly specific for small HCCs in cirrhosis patients. Concurrent delayed phase imaging is useful in the diagnosis of small hypovascular HCCs.     

Multicentric occurrence of hepatocellular carcinoma: In terms of pathology study

The remarkable advances in diagnostic techniques and in the pathomorphologic study of minute hepatocellular carcinomas (HCCs) in the early stage indicate that many HCCs are multicentric in origin. Morphologically, combinations of HCC nodules and other nodules, such as adenomatous hyperplasia containing cancerous foci, well-differentiated HCC, or well-differentiated HCC containing moderate or poorly differentiated cancerous tissue are considered to originate and proliferate in situ. These combinations are considered to be HCC of synchronous multicentric origin. We found that, in HCC associated with liver cirrhosis, 6 of 74 consecutively resected HCCs (8.3%) and 4 of 8 autopsy cases (50%) satisfied the above criteria for multicentric origin. This discrepancy between surgical and autopsy cases can be explained thus: In surgical cases, morphologic examination is limited to only the vicinity of the main tumor and patients with multiple minute tumors HCC tend not to be sent to the operation table. Thus, the frequency seen in autopsy cases may reflect the true figures for multicentric origin. In 94 HCCs associated with chronic hepatitis, we found none showing coexistence of the above nodules that are suggestive of synchronous multicentric origin.     

Study of sonographic findings of small hepatocellular carcinoma based on its pathologic findings]

Sonograms of 282 cases of hepatocellular carcinoma (HCC) less than 5 cm in size were examined. Among these, 73 cases of resected or biopsied HCCs were compared in terms of their pathologic findings and sonograms. Low echoic pattern was the more common among smaller HCCs, and low echoic periphery pattern tended to prevail with increasing size. The pathologic factors of fatty change and clear cell formation are responsible for elevating the echo level. Among HCCs less than 2 cm, the low echoic group is more differentiated than the iso-echoic group by Edmondson's classification. "Lateral acoustic shadow", "nodule in nodule", and "septum" are characteristic findings in HCC by sonography, and they correspond to the pathologic findings. However, "posterior echo enhancement" was not seen to be specific for HCC, as it was also observed with similarly frequency in hemangiomas.     

Multicentric occurrence of hepatocellular carcinoma: diagnosis and clinical significance

To evaluate current knowledge on the multicentric occurrence (MO) of hepatocellular carcinoma (HCC) and its clinical significance was the purpose of this review. The criteria for MO of HCC are defined as follows: (1) the recurrent tumor consists of well differentiated HCC occurring in a different hepatic segment from moderately or poorly differentiated preexisting HCC, (2) both the primary and recurrent tumors are well differentiated HCC, (3) the recurrent tumors contain regions of dysplastic nodules in peripheral areas and, (4) multiple HCCs, indicating the “nodule‐in‐nodule” form, in which nodules consisting of moderately or poorly differentiated HCC cells are contained in a nodule of well differentiated HCC cells. However, these criteria assume rare or no metastasis of well differentiated HCC, and are also not applicable to cases in which some HCCs of multicentric origin are rapidly dedifferentiated, presenting morphologic features of moderately or poorly differentiated tumors. Diagnostic methods, besides histopathologic methods, for determining multicentric origin in multiple HCCs in the liver, or recurrent tumor(s) of HCC, include clonal analysis of the integration pattern of hepatitis B virus (HBV) DNA in HBV carrier patients, and analysis of thep53 mutation patterns or loss of heterozygosity of chromosomal DNA. The prognosis of patients with MO of HCC after curative resection is significantly better than that of patients with intrahepatic HCC metastasis. Moreover, the Liver Cancer Study Group of Japan has reported that patients with hepatic resection for small‐sized HCCs showed higher survival rates than a nonsurgical treatment group. Consequently, HCC with MO, whether this is synchronous or metachronous, should be surgically removed as the treatment of first choice.     

Role of immunosuppression and tumor differentiation in predicting recurrence after liver transplantation for hepatocellular carcinoma： A multicenter study of 412 patients

INTRODUCTION Hepatocellular carcinoma (HCC) is one of the most common neoplasms and its incidence is currently rising worldwide[1-3]. HCC usually occurs in cirrhotic livers and less than 30% of patients presenting with HCC are considered candidates for re…     

Relationship of histologic grade of hepatocellular carcinoma (HCC) to tumor size, and demonstration of tumor cells of multiple different grades in single small HCC

The histologic features of 65 surgically resected cases of hepatocellular carcinoma (HCC) were studied, and the cellular differentiation was graded from I to IV according to Edmondson-Steiner's classification. HCC cells of 2 or more grades were seen in 31 (47.7%) of the 65 cases. There was no significant difference in the proportion of HCC composed of tumor cells of more than one histologic grade between HCCs with association with liver cirrhosis and without cirrhosis. Among these 31 cases, extremely well-differentiated HCC, corresponding to Edmondson-Steiner's grade I carcinoma, was found in 9 of 11 tumors smaller than 3 cm in diameter, but it was not seen in 20 tumors larger than 3 cm in diameter. In the 34 HCCs with a uniform histologic pattern, all of two minute tumors smaller than 1 cm in diameter consisted of extremely well-differentiated HCC, but there were no cases consisting of extremely well-differentiated HCC in tumors larger than 2 cm in diameter. Taken together, these findings suggest that HCCs originate as relatively well-differentiated tumors, which may be difficult to distinguish from adenomatous regenerative nodules, and become progressively less differentiated at a later stage of their development.     

Early Stage Hepatocellular Carcinoma Detected during Intraoperative Ultrasonography

Objectives: Recently, it has been recognized that there are increasing incidences of hepatocellular carcinoma (HCC) multicentricity. Thus, intraoperatively detected hepatic lesions that were once thought to be metastatic lesions now need to be carefully reexamined to determine whether they are true metastatic lesions or the multicentric development of HCC. Methods: We investigated the histological characteristics of small nodular lesions detected during intraoperative ultrasonography in 33 consecutive patients with small HCC wbo underwent laparotomy at our institution. Results: Fourteen nodular lesions were found incidentally in 10 of 33 patients (30.3%), and were classified into tbe following three groups: 11 nodules in nine patients (27.3%) were HCC, two nodules in two patients (6.1%) were hemangioma, and one nodule in one patient (3.0%) was a large regenerative nodule. HCC therefore comprised 78.6% of tbe intraoperatively detected nodular lesions. Of the 11 HCCs, six were hyperechoic, four were hypoechoic, and one was isoechoic. Five (83.3%) of six small hyperechoic HCCs and two (50.0%) of four hypoechoic HCCs were well differentiated and retained their preexisting liver structure. Tbese findings closely coincide with the characteristics of early stage HCC. Thus, early stage HCC comprised 63.6% of tbe intraoperatively detected HCC cases. Conclusions: A certain proportion of small satellite HCCs detected during intraoperative ultrasonography in patients with small HCC, which were previously thought to be metastatic lesions from tbe main HCC, may instead he early stage HCCs. Such findings would also support the concept of the multicentric development of HCC. Approximately 60% of all small HCC cases detected intraoperatively may be early stage HCC. As a result, it is predicted that the emergence of HCC is either multicentric or unicentric, with early intrabepatic spread, altbough the former seems to be more common.     

Multistep and multicentric development of hepatocellular carcinoma: histological analysis of 980 resected nodules

BACKGROUND/AIMS: Histological observations support the concept of multistep and multicentric development of hepatocellular carcinoma (HCC) in cases of chronic liver disease. However, the relationship between the incidence of such a modality of development of HCC and the type of background liver disease has not been fully investigated. METHODS: A total of 980 HCC nodules resected from 664 patients were analyzed. Multistep HCC was defined as well differentiated HCC containing the portal tracts (early HCC), or the presence of early HCC-like areas in the periphery of the nodule. In cases with multiple nodules, if the smaller nodule showed the features of multistep HCC, or if each nodule showed a distinct histology, the case was defined to have multicentric HCC. RESULTS: Of the 980 nodules, 369 (37.7%) met the criteria of multistep HCC. Of the 664 patients, 177 (26.7%) had multiple nodules that met the criteria of multicentric HCC. Both the incidences of multistep and multicentric HCC were significantly higher in HCV-Ab-positive cases than in HBs-Ag-positive cases (46.0 vs. 19.1%, P<0.001 and 34.1 vs. 16.5%, P=0.005, respectively). CONCLUSIONS: Multistep and multicentric HCC develops most frequently in patients with HCV infection.