The way we teach general pathology in Oslo, Norway

Hepatocellular carcinoma was induced in rats by administering aflatoxin B₁ (AFB₁) for 6 weeks. Malignant tumours were preceded by foci and nodules of altered hepatocytes of three histological types, composed of basophilic, eosinophilic, and vacuolated cells. In addition, there were areas of altered hepatocytes that were considered as hyperplastic. Lectins were used as histochemical markers to compare the expression of membrane glycoproteins in hepatocellular carcinomas and hepatic nodules with non-nodular or control hepatocytes. There were marked changes in the lectin-binding patterns of the hepatocellular carcinoma cells and the eosinophilic nodules. The lectin-binding patterns of basophilic nodules, vacuolated nodules, and hyperplastic areas were similar to non-nodular or untreated hepatocytes. The similarity in the lectin-binding changes of the eosinophilic nodules and hepatocellular carcinomas suggests that the eosinophilic nodules may be an early stage in the development of carcinoma.     

Morphology of foci of altered hepatocytes and naturally-occurring hepatocellular tumors in F344 rats

Summary The morphology of liver tumors of F344 rats used as controls in carcinogenesis bioassays were studied. Foci of cellular alteration composed of hepatocytes with basophilic cytoplasm were found commonly in F344 rats, 2 years of age. Eosinophilic and vacuolated foci were considerably less common. The morphology of 67 nodular hepatic lesions indicated that 54 were neoplastic nodules and 13 hepatocellular carcinomas. The majority of these tumors were composed of basophilic hepatocytes. Some of the carcinomas appeared to arise within neoplastic nodules. No tumors metastasized.     

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 β 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.     

An ultrastructural study of spontaneous and phenobarbitone-induced nodules in the mouse liver.

Male C3H/He mice were given 0 (control) or 85 mg/kg/day phenobarbitone (PB) in the diet. At 40, 60 and 93 weeks, groups of mice were killed and the ultrastructure of spontaneous and PB-induced liver nodules was examined. Treated mice showed typical centrilobular hypertrophy and eosinophilic nodules which may be considered as an end stage lesion. The nodule cells were similar in appearance to those in areas of centrilobular hypertrophy except for the presence of convoluted membranes which are considered to be indicative of proliferation. The incidence of carcinoma was not increased by PB treatment. The carcinomas from control and treated animals differed in their ultrastructure in that increased levels of smooth endoplasmic reticulum (SER) were seen in the carcinomas of the PB animals. The presence of SER proliferation in the carcinomas of PB animals suggests that carcinoma may respond to the enzyme-inducing effects of PB.     

NODULAR HYPERPLASIA WITH A CENTRAL TELANGIECTATIC FIBROSIS IN THE LIVER OF NON-CIRRHOTIC PORTAL FIBROSIS (IDIOPATHIC PORTAL HYPERTENSION)

Unusual nodules of hyperplastic hepatocytes were found In the liver of a 64-year-old woman with non-cirrhotlc portal fibrosis (idiopathic portal hypertension). These nodules were subdivded by stellate fibrous tissues which, in the center of the nodules, contained conspicuous telangiectatic lesions with congestion. The latter was consisted of markedly dilated sinusoids and fibrosis of their walls either in a lack of hepatocytes or with severly atrophic hepatic column. The lesions were different from already described focal nodular lesions in the liver. No drugs and chemicals could be identified as the causative agents. The small arterial changes, namely, hyalinization and thickening of their walls and luminal narrowing or occlusion, were found In the nodular lesions and also in the remaining hepatic tissues, and might be a causative factor for the nodular lesions.     

Utility of glypican‐3 and survivin in differentiating hepatocellular carcinoma from benign and preneoplastic hepatic lesions and metastatic carcinomas in liver fine‐needle aspiration biopsies

Glypican‐3 (GPC‐3), a membrane‐anchored heparin sulfate proteoglycan, has been shown to be expressed in ～80% of hepatocellular carcinoma (HCC) but not in benign hepatic lesions. Survivin, a novel inhibitor of apoptosis, and a prognostic marker, has also been expressed in HCC. We evaluated these two immunomarkers (GPC‐3 and survivin) in differentiating HCC from benign and preneoplastic hepatic lesions and metastatic carcinomas, comparing them to HepPar‐1 (hepatocyte paraffin‐1) in liver fine‐needle aspiration biopsies (FNAB). Immunohistochemistry for GPC‐3, survivin and HepPar‐1 was performed on 92 FNAB including HCC, hepatic cirrhosis, focal nodular hyperplasia (FNH), hepatic adenoma, dysplastic hepatic nodules and metastatic carcinomas. Immunostaining was scored as positive, if ≥10% of tumor cells stained. GPC‐3 is immunoexpressed in 56.8% of HCC, but not in benign and preneoplastic hepatic lesions, or metastatic carcinomas; whereas survivin is expressed in HCC (86.4%), benign hepatic lesions (85.7%), dysplastic hepatic nodules (100%) and metastatic carcinomas (94.3%). HepPar‐1 is immunoexpressed in HCC (72.7%), benign hepatic lesions (100%), dysplastic nodules (100%) and metastatic carcinomas (2.9%). The sensitivity and specificity of GPC‐3, survivin and HepPar‐1 for detection of HCC are 56.8 and 100%, 86.4 and 6.3%, 72.7 and 70.8%, respectively. GPC‐3 is a reliable and more specific immunohistochemical marker than survivin for the diagnosis of HCC in FNAB. HepPar‐1, although a more sensitive marker than GPC‐3, has a lower specificity for detection of HCC. Our data supports the potentially significant diagnostic utility of GPC‐3 in FNABs in differentiating primary malignant from benign and preneoplastic liver lesions, and metastatic carcinomas. Diagn. Cytopathol. 2009. © 2009 Wiley‐Liss, Inc.     

Ultrastructural characteristics of hyperplastic alterations in the liver of congenital portacaval-shunt rats

A congenital portacaval shunt was discovered in five rats. In these animals the hepatic artery was the only blood vessel perfusing the liver; the portal vein was absent. The livers were small and mainly hypoplastic, but light microscopy revealed the occurrence of focal hyperplastic alterations and occasional hyperplastic nodules. TEM and SEM showed these areas to be composed of clustered hepatocytes, separated by widened intercellular spaces. The cell membranes carried numerous pleomorphic microvilli, and the cytoplasma contained densely packed mitochondria, some of which were giant sized. Liver cells in the centrilobular region were hypoplastic. Comparison with findings of experimental portacaval anastomosis suggest that in congenital-shunt animals, the overall hypoplasia of the liver with the formation of hyperplastic areas is a consequence of the lack of portal blood.     

Ultrastructural characteristics of hyperplastic alterations in the liver of congenital portacaval-shunt rats.

A congenital portacaval shunt was discovered in five rats. In these animals the hepatic artery was the only blood vessel perfusing the liver; the portal vein was absent. The livers were small and mainly hypoplastic, but light microscopy revealed the occurrence of focal hyperplastic alterations and occasional hyperplastic nodules. TEM and SEM showed these areas to be composed of clustered hepatocytes, separated by widened intercellular spaces. The cell membranes carried numerous pleomorphic microvilli, and the cytoplasma contained densely packed mitochondria, some of which were giant sized. Liver cells in the centrilobular region were hypoplastic. Comparison with findings of experimental portacaval anastomosis suggest that in congenital-shunt animals, the overall hypoplasia of the liver with the formation of hyperplastic areas is a consequence of the lack of portal blood.     

Unusual hepatocellular lesions in primary biliary cirrhosis resembling but unrelated to hepatocellular neoplasms

Summary Structural, cellular and nuclear abnormalities of hepatocytes are a histological hallmark of well-differentiated, small hepatocellular carcinoma (HCC) or its borderline lesion. This study revealed that several hepatocellular abnormalities found in these hepatocellular neoplasms were also found in non-cirrhotic stages of primary biliary cirrhosis (PBC) in which HCC is unlikely to develop. These changes are small cell changes, consisting of the appearance of small hepatocytes arranged in thin trabecular or compact patterns with increased cellularity and basophilic cytoplasm. This was found in 36%, 71% and 100% in specimens of stages 1, 2 and 3, respectively. Large cell changes occurred and consisted of large hepatocytes with large nuclei and prominent nucleoli, found in 27%, 47% and 22% of the stages, respectively. Finally, liver cell rosettes were seen, showing variable acinar formation and present in 0%, 41% and 33% of the stages, respectively. These lesions were identified microscopically as irregularly shaped areas or vague nodules of hepatocytes without a fibrous rim, in the hepatic lobules. They showed an expansive growth or shaggy border against the surrounding hepatic parenchyma. Follow-up studies, including autopsies, failed to show development of HCC or its borderline lesion in PBC cases. Pathologists must make a diagnosis of HCC and its borderline lesion bearing in mind the occurrence of such unusual hepatocellular lesions probably of a reactive nature.     

Distribution and origin of the basement membrane component perlecan in rat liver and primary hepatocyte culture.

Basement membranes contain three major components (ie collagen IV, laminin, and the heparan sulfate proteoglycan termed perlecan). Although the distribution and origin of both collagen IV and laminin have been well documented in the liver, perlecan has been poorly investigated, so far. We have studied the distribution and cellular origin of perlecan in rat livers in various conditions as well as in hepatocyte primary culture. By immunolocalization in both adult and 18-day-old fetal liver, perlecan was found in portal spaces, around central veins, and throughout the lobule. Immunoelectron microscopy revealed its presence at the level of basement membranes surrounding bile ducts and blood vessels, and in the space of Disse discontinuously interacting with hepatocyte microvilli. Precursors of perlecan were detected in the rough endoplasmic reticulum of bile duct cells and both vascular and sinusoidal endothelial cells. Both hepatocytes and Ito cells were negative. Northern-blot analysis confirmed the lack of appreciable expression of perlecan in hepatocytes isolated from either fetal or adult livers. In 18-month-diethylnitrosamine-treated rat liver, perlecan was abundant in neoplastic nodules. Electron microscopic investigation revealed an almost continuous layer of perlecan in the space of Disse and intracellular staining in sinusoidal endothelial cells, only. Perlecan mRNAs were detectable in malignant nodules, and absent in hepatocytes from nontumorous areas. Hepatocytes expressed high levels of perlecan mRNAs only when put in culture. This expression was reduced in conditions that allow improvement of hepatocyte survival and function (ie addition of corticoids, dimethylsulfoxide or nicotinamide to the medium, or in coculture with liver epithelial cells from biliary origin). Immunolocalization by light and electron microscopy showed that deposition of the proteoglycan occurred in coculture, in basement membranelike structures located around hepatocyte cords. In vitro attachment assay of hepatocytes on purified perlecan substrate indicated that these cells may interact with the proteoglycan through integrins which belong to the beta 1 family. These data suggest that deposition of perlecan in the space of Disse requires cellular cooperation. This article on perlecan, the third major component of hepatic basement membranes, shows a unique cellular origin in the liver and, as found for both collagen IV and laminin, an expression in adult hepatocytes when place in culture.     

Sequential analysis of hepatic carcinogenesis: a comparative study of the ultrastructure of preneoplastic, malignant, prenatal, postnatal, and regenerating liver.

The objective of this study was to compare the fine structure of presumptive preneoplastic hepatocytes at various times during liver carcinogenesis with that of normal, developing, and regenerating liver and of hepatocellular carcinomas, using transmission and scanning electron microscopy. A new model of liver carcinogenesis was used in which several of the early steps are quite well synchronized. A single initiating dose of diethylnitrosamine induced isolated islands of altered hepatocytes. The cells were characterized by persistence of glycogen despite starvation, increase in smooth endoplasmic reticulum, and hypertrophic nucleoli. Following intense selection of the altered hepatocytes by dietary 2-acetylaminofluorene plus partial hepatectomy, the affected hepatocytes proliferated rapidly to produce basophilic foci. These early hyperplastic lesions revealed stellate-shaped dilated bile canaliculi lined by blebs and abnormally thick elongated microvilli, a decreased number of microvilli on the sinusoidal surface, a marked increase in smooth endoplasmic reticulum, large nucleoli, and bundles of pericanalicular microfilaments. A majority of the proliferating lesions reacquired a normal organizational pattern within several weeks after partial hepatectomy and could not be distinguished from normal liver. A small number continued to grow and become typical persistent hyperplastic nodules. These showed significant widening of intercellular spaces between hepatocytes, elongated microvilli over large regions of the cell surface, many invaginations of the cell membrane, and irregularly shaped bile canaliculi. Sequential changes in focal hyperplastic hepatocytes during carcinogenesis could be distinguished from normal, developing, and regenerating liver. The major differences involved the cell surfaces and cytoplasmic organelles. The findings are compatible with the hypothesis that a carcinogen may act by inducing alterations in a small number of hepatocytes and that hepatocellular carcinomas arise through stepwise evolutional changes in these cells.     

大鼠肝癌发生过程中胰岛素样生长因子-Ⅱ的表达及意义

目的:研究胰岛素样生长因子-Ⅱ(IGF-Ⅱ)在肝癌发生过程中的表达及意义.方法:采用二乙基亚硝胺(DEN)诱癌建立大鼠肝癌模型.应用放射免疫分析检测诱癌过程中血清IGF-Ⅱ浓度,应用免疫组织化学方法观察诱癌过程中大鼠肝组织IGF-Ⅱ的表达情况.结果:在大鼠肝癌的发生发展过程中,从肝细胞损伤期、增生-硬化期至癌变期3个阶段大鼠血清IGF-Ⅱ水平呈"高到低到高"的变化趋势;肝细胞损伤期嗜酸性变细胞中见IGF-Ⅱ阳性表达,癌变期癌灶中表达低于癌周增生灶、增生结节和非典型增生结节,而增生-硬化期阳性表达较少.结论:大鼠血清和肝中IGF-Ⅱ的高表达是肝癌发生发展过程中的早期及晚期事件,提示IGF-Ⅱ可能与肝细胞持续增殖及恶性转化有关.     

Malignant transformation of hepatic adenomas

Hepatic adenomas are benign neoplasms of the liver that occur in several well-defined clinical settings, but principally that of excess hormone exposure. They have a small but poorly characterized risk of malignant degeneration. The clinical presentation and pathological findings were reviewed for all hepatic adenomas resected between January 1, 2003 and July 1, 2006. Immunohistochemistry for p53, beta-catenin and alpha-fetoprotein (AFP) were performed on those cases with malignant transformation and exon 3 of beta-catenin was amplified and sequenced. A total of 17 hepatic adenomas were resected and 3 showed malignant transformation. All three cases were in women with an age range of 23-33 years. The clinical presentations were vague abdominal pain. Histologically, the malignant transformation occurred within otherwise typical hepatic adenomas. Two of three cases showed patchy atypia throughout the hepatic adenoma. The hepatocellular carcinoma arose as distinct nodules directly within the adenomas, effectively ruling out synchronous lesions. The hepatocellular carcinomas were unifocal in two cases and multifocal in one case with the greatest dimensions of the hepatocellular carcinoma being 2.5, 2.2, and 1 cm. Immunostains for AFP and beta-catenin were negative in both the hepatic adenomas and areas of hepatocellular carcinoma. p53 immunostaining was positive within the areas of malignant transformation in one case. No mutations or deletions were seen in exon 3 of the beta-catenin gene for either the adenomas or the carcinoma. In conclusion, two of the cases that developed hepatocellular carcinomas showed cytological atypia in the background adenoma. The hepatocellular carcinomas arose as distinct nodules within the adenomas. No common molecular pathway of hepatocellular carcinogenesis was observed by examining AFP, beta-catenin, and p53 immunostains and no beta-catenin mutations or deletions were found.     

Ito cell tumor: immunohistochemical investigations of a rare lesion in the liver of mice.

In 2 lifespan transgeneration experiments using a total of 4,682 CBA/J mice, we observed uncommon lipomatous lesions in the livers of 8 mice independent of the treatment. Macroscopically, the lesions were described as pale white areas (2) or nodules (6) during necropsy. The lesions ranged from 1 to 15 mm in diameter. Microscopically, the lesions consisted of nodular aggregations of round to spindle-shaped cells that partly caused distinct compression of the adjacent hepatic parenchyma. The tumor cells were smaller than hepatocytes and had dark oval nuclei. Many of the more spherical cells contained clear vacuoles of various sizes, which were shown to be lipid droplets by oil red O staining. In addition to Gomori's silver and Masson's trichrome staining, several immunohistochemical stains were used to characterize the origin of the proliferating cells. Tumor cells were labeled by vimentin, actin, desmin, and proliferating cell nuclear antigen. The 2 cell phenotypes showed similar staining characteristics. Increased amounts of laminin and tenascin, 2 extracellular matrix proteins of the liver, were detected within these neoplasms. Summarizing, we suggest that these tumors are of Ito cell origin.     

Transplanted hepatocytes engraft, survive, and proliferate in the liver of rats with carbon tetrachloride-induced cirrhosis

Repopulation of the cirrhotic liver with disease-resistant hepatocytes could offer novel therapies, as well as systems for biological studies. Establishing whether transplanted hepatocytes can engraft, survive, and proliferate in the cirrhotic liver is a critical demonstration. Dipeptidyl peptidase IV-deficient F344 rats were used to localize transplanted hepatocytes isolated from the liver of syngeneic normal F344 rats. Cirrhosis was induced by administration of carbon tetrachloride with phenobarbitone and these drugs were withdrawn prior to cell transplantation. Cirrhotic rats showed characteristic hepatic histology, as well as significant portosystemic shunting. When hepatocytes were transplanted via the spleen, cells were distributed immediately in periportal areas, fibrous septa, and regenerative nodules of the cirrhotic liver. Although some transplanted cells translocated into pulmonary capillaries, this was not deleterious. At 1 week, transplanted cells were fully integrated in the liver parenchyma, along with expression of glucose-6-phosphatase and glycogen as reporters of hepatic function. Transplanted cells proliferated in the liver of cirrhotic animals and survived indefinitely. At 1 year, transplanted hepatocytes formed large clusters containing several-fold more cells than normal control animals, which was in agreement with increased cell turnover in the cirrhotic rat liver. The findings indicate that the cirrhotic liver can be repopulated with functionally intact hepatocytes that are capable of proliferating. Liver repopulation using disease-resistant hepatocytes will be applicable in chronic conditions, such as viral hepatitis or Wilson's disease.     

The pathologic spectrum of gastrointestinal and hepatic histoplasmosis

We characterized the pathologic spectrum of lesions in gastrointestinal and hepatic histoplasmosis by studying cases of disseminated disease in immunocompromised and immunocompetent patients from endemic and nonendemic areas. We evaluated 56 specimens from 52 patients with H&E and silver stains. Of these patients, 43% presented with gastrointestinal rather than pulmonary symptoms. Thirty-one percent had gastrointestinal lesions, 10% had liver lesions, and 43% had both. Gross gastrointestinal features included ulcers (49% of patients), nodules (21%), hemorrhage (13%), obstructive masses (6%) and normal mucosa (23%). Microscopic gastrointestinal findings included diffuse lymphohistiocytic infiltration (83%), ulceration (45%), lymphohistiocytic nodules (25%), or minimal inflammatory reaction (15%) but only rare well-formed granulomas (8.5%). The most common hepatic finding was portal lymphohistiocytic inflammation; discrete hepatic granulomas were seen in less than 20% of involved livers. The pathologist must be aware of the broad range of gastrointestinal and hepatic lesions produced by histoplasmosis and, in particular, that well-formed granulomas are rare. Given the appropriate clinical context, histoplasmosis should be considered in both immunocompetent and immunocompromised patients, regardless of pulmonary symptoms, in nonendemic as well as endemic areas.     

Rapid Emergence of Carcinogen-Induced Hyperplastic Lesions in a New Model for the Sequential Analysis of Liver Carcinogenesis

Hyperplastic liver lesions which develop following administration of hepatocarcinogens have been implicated as probable precursors for the cancers which ultimately develop. Some, and possibly all, of these putative precursor lesions are resistant to the necrogenic and growth-inhibitory action of hepatocarcinogens and other hepatotoxins. An in vivo assay system based on this resistance phenomenon has been developed which encourages the rapid selective growth of carcinogen-altered hepatocytes, facilitating their early identification. The system consists of a) single carcinogenic dose of diethylnitrosamine (DEN), b) short-term dietary exposure to 2-acetylaminofluorene (2-AAF) sufficient to suppress growth of virtually all normal hepatocytes, and c) partial hepatectomy (PH) to actuate rapid growth of DEN-altered hepatocytes not suppressed by 2-AAF. Following PH, the DEN-altered hepatocytes grow out as basophilic foci which are distributed randomly throughout the 2-AAF-suppressed parenchyma. Within 1 week they can be seen as tiny, discrete, translucent nodules on the capsular and cut surface of the remaining lobes. The lesions continue to proliferate and become histologically indistinguishable from typical carcinogen-induced hyperplastic liver nodules frequently described in the literature. These in turn appear to be precursor lesions for at least some hepatocellular carcinomas. Future experimentation based on this phenomenon of “selective resistance to cytotoxicity” should prove valuable in answering specific questions about the carcinogenic process in liver and possibly in other tissues.     

Transgenic hepatocarcinogenesis in the rat.

Although transgenic hepatocarcinogenesis has been accomplished in the mouse with a number of genetic constructs targeting the oncogene to expression primarily in the liver, no example of this process has yet been developed in the rat. Because our understanding of the multistage nature of hepatocarcinogenesis is most advanced in the rat, we have developed a strain of transgenic rats carrying the promoter-enhancer sequences of the mouse albumin gene linked 5' to the simian virus-40 T antigen gene. A line of transgenic rats bearing this transgene has been developed from a single founder female. Five to six copies of the transgene, possibly in tandem, occur within the genome of the transgenic animals, which are maintained by heterozygous matings. Livers of transgenic animals are histologically normal after weaning; at 2 months of age, small foci of vacuolated cells appear in this organ. By 4 months of age, all animals exhibit focal lesions and nodules consisting primarily of small basophilic cells, many of which exhibit considerable cytoplasmic vacuolization. Mating of animals each bearing the transgene results in rats with a demyelinating condition that develops acutely in pregnant females and more chronically in males. Ultrastructural studies of these cells indicate that the vacuoles contain substantial amounts of glycogen, with the cells resembling hepatoblasts. Malignant neoplasms with both a glandular and a hepatoblastoma/hepatocellular carcinoma pattern arise from the nodules. Enzyme and immunohistochemical studies of all lesions reveal many similarities in gene expression to comparable lesions in rats subjected to chemically induced hepatocarcinogenesis, with certain exceptions. The placental form of glutathione-S-transferase is absent from all lesions in the transgenic animal, as is the expression of connexin 32. A significant number of lesions express serum albumin, and many, but not all, exhibit the T antigen. Lesions expressing the T antigen also contain stainable amounts of the p53 gene product; by contrast, normal hepatocytes express only very low levels of the T antigen within their nuclei and no demonstrable p53. All of the animals develop hepatic lesions, and approximately one-third also develop adenomas and carcinomas derived from the islet cells of the pancreas. Although there are differences in the morphology, biology, and genetic expression in early and late hepatic lesions in this strain of transgenic rat, many similarities also occur, making this a potential model system with which to study the interactions of environmental factors with a genetic program for hepatocarcinogenesis.     

Multicystic biliary hamartoma: a hitherto undescribed lesion

In this report, we presented 3 cases of unusual hamartomatous nodules of the liver. These nodules were located around hepatic capsule of the left hepatic lobe and characteristically protruded from the liver. Histologically, these nodular lesions consisted of ductal structures, periductal glands, and fibrous connective tissues containing blood vessels. Smooth muscle bundles focally surrounded ductal structures. Bile-like materials were observed within some ducts. Two cases were associated with xanthogranulomatous inflammation around bile-like materials, and this inflammatory process extended from ductal lumens to periductal connective tissues. In contrast, the remaining case, which was not associated with inflammation, showed a honeycomb appearance. Ductal epithelium and periductal glands resembled biliary epithelium and peribiliary glands, respectively, and they also expressed biliary-type cytokeratins such as cytokeratins 7 and 19. These nodules shared pathologic characteristics of ciliated hepatic foregut cysts, such as their location (around the falciform ligament) and periductal smooth muscle bundles, but did not fulfill the diagnostic criteria (no ciliated cells and multilocular lesions). These hamartomatous nodules of the liver did not fit into any of the described categories of hepatic nodular lesions. At present, we speculate that these lesions might be related to developmental abnormalities of the biliary tract or embryonal foregut.