Biomedical subjects

O Nakashima

Publications and source records attributed to O Nakashima.

At least 37 records · Page 2Linked to original sources

PubMed1999

Vascularization of small hepatocellular carcinomas: correlation with differentiation.

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 < or =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 < or =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.

Actins↗

PubMed1999

Inducible nitric oxide synthase can be induced in the absence of active nuclear factor-kappaB in rat mesangial cells: involvement of the Janus kinase 2 signaling pathway.

The contribution of nuclear factor-kappaB (NF-kappaB) and interferon-gamma (IFN-gamma) signaling to nitric oxide generation is not completely understood. The effect of NF-kappaB release and its inhibition on nitrite production and the involvement of Janus kinase 2 (JAK2) in inducible nitric oxide synthase (iNOS) induction were investigated. The following assays were performed. (1) Nitrite produced by rat mesangial cells in primary culture was measured in incubations with tumor necrosis factor-alpha (TNF-alpha) or lipopolysaccharide (LPS), with or without IFN-gamma. Cells were stimulated with TNF-alpha or LPS plus IFN-gamma in the presence of NF-kappaB inhibitors, herbimycin A (HerA), or the more specific JAK2 inhibitor AG490. (2) Immunoblotting was performed against the p65 and p50 subunits of NF-kappaB and iNOS. (3) Electrophoretic mobility shift assays were performed against NF-kappaB in the presence of NF-kappaB inhibitors or AG490. (4) iNOS promoter activity was measured in the presence of AG490 or JAK2 antisense oligonucleotides. TNF-alpha or LPS alone did not induce nitrite production, but with IFN-gamma these compounds did induce nitrite production. Pyrrolidine dithiocarbamate (PDTC), N-acetyl-L-cysteine, dexamethasone (Dex), HerA, and AG490 partially inhibited LPS/ IFN-gamma- or TNF-alpha/IFN-gamma-induced nitrite production. p65 was inhibited by the three NF-kappaB inhibitors described above, whereas p50 was not. PDTC and Dex completely inhibited the p65/p50 heterodimer, but HerA and AG490 had little effect on p65/p50. AG490 and JAK2 antisense oligonucleotides suppressed iNOS promoter activity. It can be concluded that (1) iNOS can be induced without active NF-kappaB; (2) Dex, acetylsalicylic acid, and PDTC inhibit only p65; and (3) JAK2 is involved in iNOS induction, and the contribution of JAK2 to nitrite production is greater than that of NF-kappaB.

Animals↗

PubMed1998

Clinicopathological study on hepatocellular carcinoma with lymphocytic infiltration.

We examined the clinicopathologic features of 11 surgically resected hepatocellular carcinomas (HCCs) less than 3 cm in diameter with marked inflammatory cell infiltration (LHCCs). In comparison with the other 152 HCCs without such an infiltration (controls), there were no significant differences in male/female ratio, age, serum alpha-fetoprotein levels, and laboratory and imaging findings. All the 11 LHCC cases were hepatitis B surface antigen (HBsAg) negative and hepatitis C virus antibody positive. Among the 152 controls, 116 cases were also HBsAg negative and HCVAb positive and were referred to as HCV-only controls. The clinical features were not significantly different between the LHCC and the HCV-only controls. The LHCC group tended to have higher numbers of lymphocytes and monocytes in pre- and post-operative peripheral blood, but there were no significant group differences. Recurrence rate was 9.1% in the LHCC group, 47.7% in the controls and 47.5% in the HCV-only controls (P < .01). Five-year survival rate was 100% in the LHCC group, 65.1% in the controls and 68.1% in the HCV-only controls (P < .01). Histologically, remarkable inflammatory cell infiltration, mostly lymphocytic, was observed in the cancerous tissue of the LHCC group. Varying degrees of piecemeal necrosis of cancer nests produced by infiltrating lymphocytes were observed in all the 11 cases. Lymph follicle formation was also found in 10 of 11 cases (90.9%). Liver cirrhosis was associated in 6 LHCC cases (54.5%), in 117 control cases (77.0%), and in 91 HCV-only controls (78.4%). Tumor invasion into the portal vein in the vicinity of the tumor was found in 1 LHCC case (9.1%), in 54 controls (35.5%), and in 34 HCV-only controls (29.3%). Immunohistochemically, most of the infiltrating lymphocytes, other than those in the lymph follicle, were identified as T lymphocyte, and CD8+ T lymphocyte was more predominant than CD4+ T lymphocyte. Better prognosis of the LHCC group could attribute to the anti-tumor effect induced by cellular immunity of CD8+ and CD4+ T lymphocytes, and partly by humoral immunity of B cells which formed lymph follicles.

Adult↗

PubMed1998

Angioarchitecture and blood circulation in focal nodular hyperplasia of the liver.

BACKGROUND/AIMS: We sought to clarify important unresolved points regarding angioarchitecture and blood circulation in focal nodular hyperplasia. METHODS: Twenty-nine surgically resected focal nodular hyperplasia lesions were examined histologically, immunohistochemically, and radiologically. In three autopsy cases, red- and blue-colored gelatin was injected into the hepatic artery and the portal vein, respectively, to demonstrate the vasculature in focal nodular hyperplasia. RESULTS: Histologically, no orientation with respect to portal tracts and central veins was evident in any lesion. Within lesions, vessels were classified as: (i) anomalous arteries in the fibrous septa, (ii) capillaries in the fibrous septa, or (iii) venous vessels located mainly in the parenchyma. Vessels and sinusoids adjacent to fibrous septa were stained for CD 34 and von Willebrand factor. The anomalous arteries were connected to the capillaries. Capillaries in the fibrous septa were connected to sinusoids adjacent to fibrous septa. Venous vessels were connected to central or hepatic veins surrounding the lesions. Intranodular sinusoids were connected to the sinusoids in the surrounding normal liver. Red-colored gelatin, injected at autopsy into the hepatic artery, appeared not only in the anomalous arteries but also in capillaries and in sinusoids adjacent to the fibrous septa of the lesion. Angiography clearly depicted hepatic veins located near the lesions in nine cases. Computed tomography during arterial portography disclosed no portal blood flow in the lesions. CONCLUSIONS: In focal nodular hyperplasia, arterial blood flows from the anomalous arteries via the capillaries into sinusoids adjacent to fibrous septa. The blood in the sinusoids drained to the hepatic vein either directly or via perinodular sinusoids.

Adult↗

PubMed1998

Cyclin D1, p16, and retinoblastoma gene regulate mitogenic signaling of endothelin in rat mesangial cells.

To elucidate the mechanisms by which endothelin (ET)-1 induces proliferation of mesangial cells, we investigated the involvement of the first gap phase of the cell cycle (G1) cyclin, cyclin-dependent kinase 4 (CDK4) activity, and the retinoblastoma gene product (pRb) in ET-1-stimulated cell cycle progression. In the present study, ET-1 stimulated CDK4 activity and cell cycle progression via ET A-type receptors and induced cyclin D1 mRNA and protein expression in rat mesangial cells. We also found that ET-1 stimulation of mesangial cell proliferation was inhibited by antisense oligonucleotides directed against cyclin D1 and by overexpression of a nonphosphorylatable form of pRb. To investigate the functional roles of p16INK4 and p21cip1 in ET-1-stimulated mesangial cell proliferation, we used adenovirus-mediated gene transfer. Endothelin-1-stimulated [3H]-thymidine incorporation, CDK4 kinase activity, and the percent of cells in S phase were found to be significantly inhibited by overexpression of p16INK4 and slightly inhibited by overexpression of p21cip1. Thus, ET-1 induced cyclin D1 expression and stimulated CDK4 activity and cell cycle progression via the A-type receptor in rat mesangial cells. These effects were regulated by the expression of cyclin D1, p16INK4, p21cip1, and phosphorylatable form of pRb. The results of the present study provide the basis for further investigation of basic and therapeutic approaches towards mesangial proliferative diseases.

Animals↗

PubMed1998

Cyclins and the cyclin-kinase system--their potential roles in nephrology.

Our understanding of the cell-cycle mechanisms has progressively advanced in the past few years. Cyclins and cyclin-dependent kinases play major roles as positive cell-cycle regulatory proteins and CDK inhibitors; while the Kip family and INK4 family are negative regulatory proteins in mesangial cells and renal tubular cells. An understanding of the cell cycle is essential for the rational design of novel pharmacotherapeutic approaches to suppress the excessive proliferation of mesangial cells in glomerular disease and hypertrophic tubular disease.

Animals↗

PubMed1998

Schwannoma of the liver: report of two surgical cases.

Two surgical cases of benign schwannoma of the liver were examined: A 64-year-old female who was admitted to hospital for the treatment of early gastric cancer (case 1) and a 69-year-old female who had pitting edema in the legs (case 2). Diagnostic imaging revealed large solid masses located in the caudate lobe through to the left lobe of the liver in case 1 and in the left lobe in case 2. Both patients showed no signs of von Recklinghausen's disease. Partial hepatectomies were performed and the maximum diameter of their resected hepatic tumors was 4 cm and 15 cm, respectively. Histologically, the well-demarcated tumors were yellowish in color, elastic-hard in consistency and consisted predominantly of short spindle-shaped cells proliferating in an interlacing fashion. The tumor lesions were separated by fibrous bands and surrounded by a lymphoid cuff. Immunohistochemically, the tumor cells were positive for S-100 protein. The tumors were diagnosed as benign hepatic schwannoma.

Aged↗

PubMed1998

An unusual hyperplastic hepatocellular nodule in a patient with hepatitis C virus-related liver cirrhosis.

Recent advances in diagnostic imaging techniques have increased the likelihood of detecting novel nodular lesions of the liver. We report here a case of unusual hyperplastic hepatocellular tumor found in a 70-yr-old woman with hepatitis C virus-related cirrhosis. A mass was incidentally detected in the right lobe by abdominal ultrasonography and confirmed by computed axial tomography (CT). Magnetic resonance imaging demonstrated that the tumor had hyperintense signal with a small hypointense region in the center and a thin, hypointense rim on T1-weighted image and a hypointense signal on T2-weighted image. CT during hepatic arteriography showed that the tumor was hypodense with a central hyperdense region, whereas CT during arterial portography revealed that the tumor was isodense and surrounded by a thin circular hypodense band with a central hypodense region. These radiographic findings suggested a diagnosis of dysplastic nodule with malignant foci of hepatocellular carcinoma. The patient underwent tumor resection. Macroscopically, the tumor, 45 x 45 x 30 mm in size, was encapsulated and had a central stellate-like scar with radiating septa. Histological examination showed a hyperplastic hepatocellular tumor without cellular, nuclear or structural atypia. The central fibrous scar contained abundant small, artery-like and vein-like vessels, whereas there were no normal portal triads but rather several portal tract-like structures lacking bile ducts in the parenchyma of the tumor. Some of the portal tract-like structures were composed of artery-like and vein-like vessels, and the others possessed vein-like vessels only. There were no bile ducts in the tumor. The nontumorous liver tissue had evidence of macronodular cirrhosis. Finally, this tumor was regarded as an unusual type of hyperplastic hepatocellular nodule encountered in cirrhotic liver, characterized by the presence of central stellate-like fibrosis and the lack of bile ducts. Although the pathogenesis of the hyperplastic lesion is unclear, it may represent a focal regenerative hepatocellular response to localized circulatory disorder.

Aged↗

PubMed1998

Lovastatin inhibits mesangial cell proliferation via p27Kip1.

Mesangial cell proliferation is a key feature of glomerulonephritis. The hydroxymethylglutaryl-coenzyme A reductase inhibitor lovastatin is known to inhibit cell cycle progression. To determine the inhibitory mechanisms of mesangial cell proliferation by lovastatin, the cyclin-dependent kinase (CDK) activity, and expression of CDK inhibitor (p27Kip1, p21Cip1, and p16INK4) mRNA and protein were measured. Lovastatin inhibited phosphorylation of retinoblastoma protein and mesangial cell proliferation dose dependently. Lovastatin increased the p27Kip1 protein level but produced no changes in the abundance of the p27Kip1 mRNA level both in the presence and absence of mitogens. Treatment with lovastatin revealed the increment of both CDK2- and CDK4-bound-p27Kip1. The experiment using antisense oligonucleotide against p27Kip1 showed significant amelioration of lovastatin-induced cell cycle arrest. Lovastatin reduced both platelet-derived growth factor-stimulated CDK2 and CDK4 kinase activities. In conclusion, lovastatin inhibited mesangial proliferation via translational upregulation or impairment of p27Kip1 protein degradation. Lovastatin serves as a potential therapeutic approach to mesangial proliferative disease.

Animals↗

PubMed1998

p53 overexpression in small hepatocellular carcinomas containing two different histologic grades.

There is evidence to suggest that a focus of less-differentiated hepatocellular carcinoma (HCC) may arise within a pre-existing well-differentiated HCC, eventually replacing it. In the present study, the p53 tumor suppressor gene was analyzed by immunohistochemistry in 31 hepato-cellular carcinomas (HCCs) containing two or more regions in the same nodule with different histologic grades. p53 was overexpressed in the nucleus in 13 of 31 HCCs (42%), in seven of which p53 overexpression was seen only in the less-differentiated area of the tumor. This suggests that overexpression of presumed mutant p53 may have contributed to dedifferentiation during the development of HCC.

Adult↗

PubMed1997

Overexpression of cell cycle inhibitors (p16INK4 and p21Cip1) and cyclin D1 using adenovirus vectors regulates proliferation of rat mesangial cells.

To elucidate the mechanisms of the cell cycle of mesangial cells, adenovirus vectors containing coding sequences of cyclin D1 (AxCAD1), p16INK4 (AxCAp16) and p21Cip1 (AxCAp21) were produced and investigated to determine whether transfer of these genes changes serum- and PDGF-induced proliferation of rat mesangial cells. Efficiency of the transfer of the genes was examined by Northern and Western blot analyses. The cell cycle of mesangial cells was evaluated by measurement of [3H]-thymidine incorporation, flow cytometry, and cyclin-dependent kinase 4 kinase assay. Expression of cyclin D1, p16INK4 and p21Cip1 was observed from 24 h after the infection, and the expression increased up to 48 h. AxCAp16 and AxCAp21 caused a significant inhibition in the [3H]-thymidine incorporation to 47% and 76%, respectively. AxCAp16 and AxCAp21 also inhibited the mitogen-induced increase in cyclin-dependent kinase 4 kinase activity and reduced the percentage of cells in S phase. Coinfection of AxCAp16 with AxCAp21 showed no additive inhibition. Overexpression of cyclin D1 reduced cell size and increased the percentage of the cells in S and G2 phase. These findings suggest that p16INK4 and p21Cip1 function as inhibitors of the proliferation of mesangial cells induced by growth-promoting factors and that deregulated expression of cyclin D1 causes cell cycle disturbances. Adenovirus-mediated gene transfer of p16INK4 and p21Cip1 serves as a potential therapeutic approach to mesangial proliferative diseases.

Adenoviruses, Human↗

PubMed1997

Expression of PDGF and PDGF receptor mRNA in glomeruli in IgA nephropathy.

This study investigated the mRNA expression of the platelet-derived growth factor (PDGF) A-chain and B-chain and PDGF-beta receptor in glomeruli of 15 immunoglobulin A (IgA) nephropathy kidneys and those with minimal-change lesion (N = 7), membranous nephropathy (N = 3), and focal segmental glomerulonephritis (N = 5), by using competitive RT-PCR methods. The level of PDGF B-chain and beta receptor mRNA expression in IgA nephropathy was significantly higher than in the other forms of glomerulonephritis, but mRNA expressions of PDGF A-chain were not significantly different. Significant correlations were observed between the urinary protein level and the mRNA level of PDGF-beta receptor expression and PDGF B-chain expression, and between the serum creatinine level and the mRNA level of PDGF-beta receptor expression. The PDGF B-chain and beta-receptor may be upregulated and accelerate cell proliferation in a paracrine or autocrine manner and may play a role in the pathogenesis of IgA nephropathy.

Becaplermin↗

PubMed1996

Pathomorphological study of Kupffer cells in hepatocellular carcinoma and hyperplastic nodular lesions in the liver.

A pathomorphological study was conducted to clarify the localization of Kupffer cells in hepatocellular carcinoma (HCC) tissues and such hyperplastic nodular lesions as adenomatous hyperplasia (AH) and focal nodular hyperplasia (FNH). Materials were surgical specimens of 50 HCCs, 7 AHs, and 13 FNHs. These tissues were immunohistochemically stained with an anti-human macrophage antibody (anti-CD68 antibody). Among CD68-positive cells, short spindle-shaped cells were considered as Kupffer cells, and Kupffer cell numbers in tumor lesions and surrounding liver tissues of each specimen were comparatively examined. As a result, the number of Kupffer cells in well-differentiated HCC tissues less than 1 cm in diameter was 27.8 +/- 3.3 (mean +/- SE/025 mm2); in noncancerous tissues, it was 302 +/- 3.2, showing no statistically significant differences. The number of Kupffer cells in cancerous tissues decreased in comparison with the number in noncancerous tissues, as the tumor size increased and histological grade decreased. In hyperplastic nodular lesions, the number was higher in nodular lesions than in the surrounding liver tissues in 4 of 7 AHs (57.1%) and 6 of 13 FNHs (46.2%). This could explain the reason why enhanced MRI, which utilizes the selective taken-up mechanism of chondroitin sulfate iron colloid and superparamagnetic iron oxide into the reticuloendothelial system of the liver and spleen, depicts well-differentiated HCC and AH at the same signal intensity as in the surrounding liver tissues. Our findings also indicate that there is a limitation in differentiating or diagnosing small HCC and hyperplastic nodular lesions by using enhanced MRI, which utilizes Kupffer cell functions.

Carcinoma, Hepatocellular↗

PubMed1996

Role of urinary arginine vasopressin in the sodium excretion in patients with chronic renal failure.

Patients with chronic renal failure show almost equal levels of sodium excreted in the urine as healthy subjects through an increase of the fractional excretion sodium (FE(Na)). The mechanisms of this adaptation, however, are unknown. Recently, urinary arginine vasopressin (AVP) has been shown to inhibit the antidiuretic action of plasma AVP in the collecting ducts of rabbits and rats. In this article, the roles of plasma and urinary AVP are examined with other hormones in the sodium excretion of 57 patients with chronic renal disease. The fractional excretion of AVP, plasma atrial natriuretic peptide (ANP) and endothelin-1 (ET-1), urinary ET-1, and FE(ET-1) correlated with the decrease of creatinine clearance (Ccr). Multiple and stepwise regression analyses showed that FE(AVP) is the major dependent determinant for FE(Na) (adjusted r2 = 0.78). These results suggest that the increase of AVP excretion per remaining nephron could be a cause of the increase of FE(Na) in patients with renal failure. Although plasma AVP works as an antidiuretic hormone, urinary AVP serves as an intrinsic diuretic, especially in patients with chronic renal failure.

Adolescent↗

PubMed1996

A clinicopathological study on combined hepatocellular and cholangiocarcinoma.

We clinicopathologically studied 23 surgically resected cases of combined hepatocellular and cholangiocarcinoma (HCC-CC). The frequency of this cancer in our subjects, who had primary liver cancer and who underwent hepatectomy, was 6.3%. The mean age of patients was 64.0 years old and the male: female ratio was 1.9:1. Serum alpha-fetoprotein was positive in 70% of cases and its levels were relatively low (< or = 1000 ng/mL) in most cases. The positive rate of serum carcinoembryonic antigen was 18% and its levels were also low. In regard to hepatitis virus markers, 17% of the 20 combined HCC-CC cases were positive to HBs antigen and 70% were positive to the HCV antibody. Of the 23 combined HCC-CC cases, 9 cases (39%) were associated with liver cirrhosis. Tumours were classified macroscopically into a separated type (HCC and CC are clearly separated 17%), a HCC-predominant type (resembles HCC 49%), and a CC-predominant type (resembles CC 34%). The separated and HCC-predominant types were associated with liver cirrhosis in 50 and 55% of cases, respectively. These cases with liver cirrhosis presented the features of HCC more apparently, while those without liver cirrhosis presented the features of CC. Histologically, all cases were classified into either Type I (HCC and CC were clearly distinguished; 17%), Type II (HCC and CC were contiguous and shared transitional features; 66%), and Type III (cancer cells were able to be evaluated as either HCC or CC and were considered to be an intermediate type; 17%). Immunohistological stains for cytokeratin were useful to distinguish HCC and CC. Specifically, CC was positive to cytokeratin 7 and 19. The tumour, in which HCC and CC were almost indistinguishable, such as Type III), indicates the presence of intermediate tumour cells that can differentiate either to HCC or CC.

Aged↗

PubMed1996

Clinicopathologic study on clear cell hepatocellular carcinoma.

In order to study the clinicopathologic characteristics of the clear cell variant of hepatocellular carcinoma (HCC), 215 consecutive cases measuring less than 5 cm in diameter were reviewed. The cases were divided into clear cell HCC (20 cases); focal clear cell HCC (77 cases); and non-clear cell HCC (118 cases). Clinical and pathological findings were compared among these groups. Clear cell HCC was moderately differentiated in 80% of cases and the incidence was not related to tumor size. The male to female ratio was 2.3:1, lower than the 6.9:1 of non-clear cell HCC. The association rate with liver cirrhosis was 90%, higher than the 59.3% of non-clear cell HCC. Three- and five-year survival rates, and no recurrence time were 54.5%, 33.3%, and 564 days, respectively, lower than the findings of 74.3%, 46.1%, and 770 days for non-clear cell HCC. But there is no significant difference in prognosis between both groups. Ultrastructurally, clear cells showed abundant glycogen storage and a variable degree of fat vacuoles, with a marked reduction of the number and size of organelles in the 8 cases examined. Non-clear cells of focal clear cell and non-clear cell HCC showed a moderate degree of glycogen storage in 85.7% and 28.6% of the seven cases examined from each group, with significant difference. It was concluded that clear cell HCC occurs mostly in the moderately differentiated form and is characterized by high female prevalence, high rate of association with liver cirrhosis, and has no significant difference in prognosis compared with non-clear cell HCC.

Adenocarcinoma, Clear Cell↗

PubMed1996

Biliary hamartomas simulating multiple hepatic metastasis on imaging findings.

We encountered a 62-year-old female with advanced gastric cancer, in whom multiple nodular lesions in the liver, which were depicted as small low density areas, less than 5 mm in diameter, on computed tomography and demonstrated as a heterogenic pattern on ultrasonograms. This patient was suspected to have multiple liver metastases of gastric cancer. She deteriorated gradually and died of respiratory failure due to lung metastasis. At autopsy these hepatic nodular lesions were biliary hamartomas. Biliary hamartoma is a lesion usually identified microscopically, and there have been only 8 cases including ours, which were depicted on images. Along with a remarkable advance in imagings, it should become more important to differentiate biliary hamartoma from malignant hepatic neoplasms on images.

Bile Duct Diseases↗

PubMed1996

[Pathomorphologic characteristics and differential diagnosis of small hepatocellular carcinoma].

Recent advances in various diagnostic imagings have made possible early diagnosis of hepatocellular carcinoma (HCC). Grossly, small HCCs of the early stage up to around 1.5 cm in diameter are vaguely demarcated from surrounding liver tissue. Such minute tumors are classified as small HCC with indistinct margins. Histologically, these tumors consist of uniform distribution of well-differentiated cancerous tissues, which are characterized by increased cell density with increased nuclear/cytoplasmic ratio, irregular thin-trabecular pattern with occasional pseudoglandular structure, and frequent fatty and/or clear cell change. In all small HCCs with indistinct margins, varying numbers of portal tracts are contained within the cancerous tissues. None of them represents invasion of the portal vein or intrahepatic metastasis. Thus, small HCC with indistinct margins is considered to be HCC of the earliest stage that can be clinically detected at this moment. Along with the increase of resected small HCCs, hyperplastic lesions such as adenomatous hyperplasia (AH) and atypical AH, which are difficult to differentiate from well-differentiated HCC have also been found. Atypical AH is considered a borderline malignancy. Some focal nodular hyperplasias and liver cell adenomas are also difficult to differentiate from well-differentiated HCC. It should be recalled that some metastatic tumors such as carcinoid tumor, renal cell carcinoma and hepatoid adenocarcinoma also resemble HCC.

Adenocarcinoma, Clear Cell↗