Epithelial and mixed hepatoblastoma in the adult. Histological observations and general considerations.

Two instances of hepatoblastoma in adults are reported, with one case representing a purely epithelial, the other a mixed epithelio-mesenchymal variant. The purely epithelial tumour, consisting entirely of so-called fetal elements, was present in the liver of a 35-year-old woman without any other hepatic changes, whereas the mixed tumour developed in the coarsely nodular liver of a 73-year-old man with a currently inactive cirrhosis. Besides the epithelial component, this case held predominantly indifferent spindle-shaped and histiocytic mesenchymal cells which frequently gave rise to osteoid and to bony trabeculae, and on occasion also to vascular structures, biliary ducts and even to groups of hepatocytes. The cytological and histological picture of both cases is comparable even in its details to that seen in the hepatoblastomas of early childhood. This concordance should be insisted upon as a diagnostic pre-condition if a mixed tumour in the adult, consisting of several components, is to be accepted as a hepatoblastoma. This similarity also enables us to recognize the purely epithelial variant of the hepatoblastoma in the older patient as belonging to this tumour category, and to separate it from other hepatic carcinomas. It is suggested that in these tumours the pluripotent cells, or the cells that have again become pluripotent, are derived from differentiated hepatocytes; no evidence in favour of the existence of a particular cellular subpopulation or of "stem cells" has been found.     

Sarcomatoid hepatocellular carcinoma with hepatoblastoma-like features in an adult

A mixed epithelial and mesenchymal tumor of the liver arising in an adult is rare and is mostly classified as sarcomatoid hepatocellular carcinoma (HCC). In this study, a case of sarcomatoid HCC in an adult with hepatoblastoma (HB)-like features, which produced difficulty in the differential diagnosis between sarcomatoid HCC and mixed HB, is presented. The epithelial component of the tumor composed of poorly differentiated HCC, Edmondson's grade III, and more primitive components, which were embryonal and small cell undifferentiated components of HB-like areas. The small undifferentiated cells surrounded HCC and the embryonal component of HB-like area, and revealed transition partly to areas of rhabdomyosarcoma. A small portion of chondrosarcoma was also noted. Immunohistochemical analysis showed that HCC and the embryonal component of HB-like areas expressed alpha-fetoprotein (AFP) and cytokeratin 8. The small undifferentiated cells were negative for AFP but stained with cytokeratin 8 as well as CD56, which is a marker of primitive cells in many sarcoma and HB. It is not certain whether small undifferentiated cells belong to hepatic progenitor cells or primitive mesenchymal cells. Polymerase chain reaction-single-strand conformation polymorphism analysis for beta-catenin mutation using microdissection revealed no mutation of any components. A review was undertaken of the cases previously reported as adult hepatoblastoma without detailed immunohistochemical study and consider many of them may be sarcomatoid HCC. These primitive and sarcomatoid components would be arising from the dedifferentiation process of HCC.     

Hepatoblastoma in an 82-year-old man. An autopsy case report

An autopsy case of adult hepatoblastoma is presented. The patient was an 82-year-old male with chronic hepatitis of 7 years' duration. The liver tumor was detected 6 months before death. Autopsy revealed a large hepatic tumor occupying about 80% of the entire liver. Histologically, the tumor showed typical features of mixed epithelial- and mesenchymal-type hepatoblastoma. The epithelial component consisted of fetal and embryonal cell types. The mesenchymal component showed primitive spindle-shaped cells with various degrees of cellularity. Chondroid areas and a few foci of osteoid formation were also present.     

Small epithelial cells and the histogenesis of hepatoblastoma. Electron microscopic, immunoelectron microscopic, and immunohistochemical findings.

The wide range of epithelial and mesenchymal lines of differentiation seen in hepatoblastoma suggests that this tumor derives from a pluripotent stem cell. To test this hypothesis, seven hepatoblastomas of various subtypes were investigated for the presence of cells with the features of the oval cells found during hepatocarcinogenesis in rodents that are thought to be closely related to hepatic stem cells. Because similar cells, referred to as "small cells," have been described in human liver disease with chronic ductular reaction, five liver biopsies from infants with biliary atresia were also investigated. The specimens were investigated by electron microscopy, immunoelectron microscopy, and immunostaining for cytokeratins 7, 8, 18, and 19. Small epithelial cells (SEC) corresponding to the oval cells of the rat and the "small cells" in humans were found in both biliary atresia and hepatoblastoma. These cells were oval and exhibited intercellular junctions, tonofilament bundles, and a biliary epithelium-type cytokeratin profile. SEC were found in small numbers in fetal hepatoblastoma and in moderate numbers in embryonal hepatoblastoma. In small cell hepatoblastoma, nearly all the tumor cells exhibited SEC-like ultrastructural features and a corresponding cytokeratin profile. Thus, cells exhibiting morphological and immunophenotypic features of hepatic stem cells are detectable in hepatoblastoma. Their numbers vary according to the subtype, reflecting the differing degrees of differentiation of the various subtypes, consistent with the theory propounded in the literature that embryonal and, with further differentiation, fetal tumor cells derive from precursor small cells. The findings support the hypothesis that hepatoblastoma derives from a pluripotent, probably entodermal or even less committed, stem cell.     

Poorly differentiated hepatocellular carcinoma accompanied by anti‐Hu antibody‐positive paraneoplastic peripheral neuropathy

The anti‐Hu antibody is one of the most famous onco‐neural antibodies related to paraneoplastic neurological syndrome, and is associated with small cell lung carcinoma in most cases. Here, we report a case of poorly differentiated hepatocellular carcinoma accompanied by paraneoplastic peripheral neuropathy positive for the anti‐Hu antibody. Image inspection before operation revealed that no tumors were found in organs other than the liver, including lung, and that the liver tumor had no metastatic lesion. The liver tumor showed histological appearance of poorly differentiated carcinoma with cartilaginous metaplasia and partial blastoid cell appearance. Most tumor cells presented trabecular‐like structure lined by sinusoidal vessels. Immunohistochemically, the tumor cells were positive for low molecular weight cytokeratin and vimentin, partially positive for cytokeratin 19 and CD56, but negative for synaptophysin, chromogranin A and alpha‐fetoprotein. Based on the trabecular‐like morphology and the results of immunohistochemical staining, we concluded that the tumor was diagnosed as poorly differentiated hepatocellular carcinoma. Anti‐Hu antibody‐positive paraneoplastic peripheral neuropathy accompanied with liver tumor is extremely rare as far as is known. The presented case indicates that poorly differentiated carcinoma has the potential to be the responsible lesion of anti‐Hu antibody‐positive paraneoplastic neurological syndrome and systemic work‐up is important for the management of this neurological disorder.     

Hepatoblastoma cells producing alpha-fetoprotein: morphometric, immunohistochemical and electron microscopic studies

Morphometric, immunohistochemical, and electron-microscopic studies were undertaken in an attempt to identify the types of hepatoblastoma cellular elements responsible for the synthesis of alpha-fetoprotein (AFP), and to see how they may relate to serum AFP levels and the metastatic spread and prognosis of the hepatoblastoma. Morphometric studies of 21 hepatoblastomas with statistical treatment of the results revealed a moderately strong reliable correlation of the AFP serum titer with the volume ratio of embryonal tumor cells and with that of those tumor elements of endodermal hepatic diverticulum which are similar to the latter cells with regard to degree of differentiation. Also, a consistent, reliable negative correlation was demonstrated between serum AFP titer and the volume of fetal hepatoblastoma cells. The volume ratio of stromal elements was found to be subject to chance variations and not to correlate with serum AFP level. Immunohistochemical and electron-microscopic studies confirmed the morphometric findings and showed AFP synthesis to be effected by poorly differentiated hepatoblastoma cells--by endodermal hepatic diverticulum elements at first and by embryonal and intermediate tumor cells later--and to decrease as the liver tumor cells differentiate further. It is concluded that a high serum AFP level is, generally, an indication that the hepatoblastoma is an extensive one and consists of poorly differentiated cells so that the prognosis is unfavorable.     

Mixed hepatoblastoma in an adult--a case report and literature review.

Hepatoblastoma is thought to originate from embryonal hepatic tissue, and most of these tumors occur in children under the age of 2 years. Hepatoblastoma in adults is extremely rare, and the prognosis is much worse than the mixed hepatoblastoma of childhood. We experienced a case of mixed hepatoblastoma in a 51 year old female patient. She had been suffering from a mild pain and a palpable lump in the epigastric area. Serum AFP was 43,850 ng/ml. Computerized tomography and selective abdominal angiography showed a large low-density mass. With a suspicion of hepatocellular carcinoma of the left lobe, a left lateral segmentectomy was performed. The external surface showed a huge protruding mass and the capsule was previously ruptured. On section, the tumor was a 11 x 7 cm sized expanding mass which had a variegated surface composed of yellow-white friable tissue with multifocal hemorrhagic areas. Microscopic examination revealed a tumor consisted of epithelial and mesenchymal elements. The mesenchymal cells were spindle in shape and proliferated over the whole tumor with focal osteosarcomatous differentiation. The epithelial components showed well-differentiated hepatocellular carcinoma-like areas, poorly differentiated acinar or tubular structures.     

Congenital hepatoblastoma of mixed type. Light and electron microscopy studies

Malignant liver tumors of infancy are uncommon. In this report the histological and ultrastructural features of a congenital mixed hepatoblastoma in a female infant are described. The tumor was obtained by radical surgery at the eighth day of life. Histologically the mass was characterized by a mixture of variously differentiated hepatic tissue and mesenchymal tissue. The epithelial component is represented by liver cells of the embryonic and fetal type. Electron microscopical investigation revealed a changing organelle composition of the epithelial tumor cells showing a decreased number of cytoplasmic organelles in the cells of the embryonic type. At cellular junctions, however, these cells are connected by desmosome-like structures without lumina as well as empty canaliculi-developing structures of cholangiolar microvilli. At light microscopical level the former corresponded to pseudorosettes , the latter to so-called rosettes. Furthermore, in places sinus-like structures are encountered but in the absence of true sinusoidal channels with Disse's spaces. Some areas consisted of undifferentiated cells lacking cytoplasmic organelles and resembled a multipotential blastema. The ultrastructural findings suggest that hepatoblastoma may arise from an undifferentiated progenitor cell capable of various forms of differentiation.     

Metastatic potential of human colon cancer cell lines: relationship to cellular differentiation and carcinoembryonic antigen production

The relationship between cellular differentiation and carcinoembryonic antigen (CEA) production by human colorectal tumor cells and their ability to form hepatic metastases was studied. Eight human colon cancer cell lines were injected into athymic mice using different routes of administration to characterize their metastatic potential. The four poorly differentiated, non or low CEA producing cell lines were poorly metastatic to the liver after intrasplenic injection. After intraperitoneal implantation the same cell lines were highly tumorigenic, and subsequently metastastic to the liver. In contrast, the four moderate to well-differentiated cell lines that produced moderate to high levels of CEA were highly metastatic to the liver following intrasplenic injection. After intraperitoneal implantation they were less tumorigenic, and metastatic to the liver. We conclude that in this system poorly differentiated non or low CEA producing colorectal cell lines have a lower metastatic capacity compared to the well-differentiated high CEA producing colorectal cell lines. These data correlate directly with the pattern of metastatic spread and clinical course observed in patients with these tumors, suggesting that degree of differentiation and level of CEA production may play a role in development of site-specific metastases.     

Small cells in hepatoblastoma lack "oval" cell phenotype.

Hepatoblastoma, a childhood tumor of the liver, is composed of epithelial and mesenchymal elements in varying proportions and at various stages of differentiation. The epithelial element recapitulates the stages of hepatocyte development from the primitive blastema through embryonal hepatocytes to fetal hepatocytes. The blastemal or undifferentiated cells have been postulated to represent neoplastic hepatocyte progenitor cells. In this study, we examine the immunophenotype of the various epithelial cells of hepatoblastoma with special emphasis on the small undifferentiated cell component and compare it with that of adult hepatocytes and hepatic stem (oval) cells. Putative stem cells in the liver can express all of the following markers: alpha-feto protein, CK19 (OV-6), chromogranin A, Bcl-2, HepPar-1, and alpha1 microglobulin. The latter, like alpha-feto protein, is a plasma protein synthesized by hepatocytes. Both alpha1 microglobulin and HepPar-1 are expressed in fetal liver cells as early as 7 weeks of intrauterine life. They are also expressed in hepatocellular carcinoma and in hepatocytic cell lines derived from normal fetal or adult liver. Formalin-fixed, paraffin-embedded archival tissues from 10 predominantly epithelial hepatoblastomas were immunostained with antibodies directed against CD 34, alpha1 microglobulin, Bcl-2, HepPar 1, and CK19 using the avidin-biotin-peroxidase method. The undifferentiated small cell component did not express any of the markers studied, namely, Bcl-2, HepPar-1, alpha(1) microglobulin, CD34, or CK19. Hepatocyte-like cells were alpha1 microglobulin- and HepPar-1-positive, with the intensity of staining correlating with the degree of hepatocytic differentiation. Bcl-2 expression was restricted to areas of ductular differentiation. CK19 was detected in foci that showed duct formation. The small cells of hepatoblastoma did not express HepPar-1, Bcl-2, CK19, alpha1 microglobulin, or CD34, markers that characterize the immunophenotype of hepatic stem cells ("oval" cells). Thus, this observation raises the following questions: (1) is "hepatoblastoma" a misnomer? (2) is the expression of tumor antigens dysregulated in hepatoblastoma? (3) does the liver have two different types of progenitor cells, oval cells and blastemal cells, with differing immunophenotypes? and (4) do the blastemal cells, rather than oval cells, represent the more primitive progenitor cells of the liver?     

Teratoid hepatoblastoma: multidirectional differentiation of stem cell of the liver

Hepatoblastoma is the most common malignant hepatic neoplasm of childhood, showing a wide spectrum of epithelial and mesenchymal components. Teratoid hepatoblastoma, which reveals multiple lines of tissue differentiation such as mucinous epithelium, melanin pigment, endocrine differentiation, glial and mesenchymal components, has rarely been observed. We report a case of teratoid hepatoblastoma in a 22-month-old girl. She had been diagnosed with hepatoblastoma through percutaneous needle biopsy of the liver and treated with 10 chemotherapy cycles of epirubicin, VP-16 and cisplatin and with hepatic artery embolization. After 10 months, an extended left lobectomy was performed. Grossly, a multinodular, partly well-demarcated, solid mass (7 x 5 cm) with dense fibrosis and focal cystic change occupied almost the entire specimen. There was extensive necrosis due to preoperative treatment. Microscopically, the tumor showed multiple lines of differentiation, which was composed of embryonal, fetal hepatocytes and mesenchymal elements with numerous foci of osteoid. There were also other components showing endodermal, neural, melanocytic and endocrine differentiation. These teratoid components were considered relatively resistant to preoperative chemotherapy, in contrast to extensive necrosis of both embryonal and fetal hepatocytes. These teratoid features of hepatoblastoma are considered to be a multidirectional differentiation of the small epithelial cells or stem cells of the tumor.     

Immunohistochemical and ultrastructural study on erythropoiesis in hepatoblastoma

Eighteen cases of hepatocellular carcinoma in children were examined, and it was found that erythropoiesis exclusively appeared in the well differentiated type of hepatoblastoma. In such foci large immature erythroblasts were found among the tumor cells, whereas mature forms tended to gather in the subendothelial spaces or within sinusoids. Desmosome-like attachments were frequently found between immature erythroblasts and tumor cells. The tumor cells were well differentiated and had a distinct polarity. The erythropoietic foci were never found in lymph nodes, spleens and in the non-neoplastic hepatic tissues obtained by surgery or autopsy. Erythroblastic cells did not show an increase in number in the bone marrows. These findings indicate that hepatoblastoma cells in certain stages of differentiation have the capacity to induce the differentiation of pluripotent hemopoietic stem cells into the cells of erythrocytic series, or that the microenvironment composed of one or more tumor cells offer good soil for the differentiation of erythroblastic cells. There seems to be no intimate relationship between the production of alpha-fetoprotein by tumor cells and the appearance of erythropoiesis.     

IMMUNOHISTOCHEMICAL AND ULTRASTRUCTURAL STUDY ON ERYTHROPOIESIS IN HEPATOBLASTOMA

Eighteen cases of hepatocellular carcinoma in children were examined, and it was found that erythropoiesis exclusively appeared in the well differentiated type of hepatoblastoma. In such foci large immature erythroblasts were found among the tumor cells, whereas mature forms tended to gather in the subendothelial spaces or within sinusoids. Desmosome-like attachments were frequently found between immature erythroblasts and tumor cells. The tumor cells were well differentiated and had a distinct polarity. The erythropoietic foci were never found in lymph nodes, spleens and in the non-neoplastic hepatic tissues obtained by surgery or autopsy. Erythroblastic cells did not show an increase in number in the bone marrows. These findings indicate that hepatoblastoma cells in certain stages of differentiation have the capacity to induce the differentiation of pluripotent hemopoietic stem cells into the cells of erythrocytic series, or that the microenvironment composed of one or more tumor cells offer good soil for the differentiation of erythroblastic cells. There seems to be no intimate relationship between the production of α - fetoprotein by tumor cells and the appearance of erythropoiesis.     

Histological and ultrastructural characteristics of primary malignant liver tumors in children

Histological and electron microscopic studies of primary malignant liver tumors in children established the differences in the morphological composition of the epithelial and mixed variants of hepatoblastoma. The epithelial component is represented by embryonal and fetal cells at different levels of ultrastructural and functional differentiation. The mixed variant of hepatoblastoma is characterized by islets of stellate and lymphocyte-like cell capable of differentiation into epithelial and mesenchymal components. The latter does not have a regular composition and may include cells differentiating both into tissues with formation of myofibrils, collagen, glycosamine-glycanes, and hematogenically with formation of hematopoietic foci and vascular structures. Hepatocarcinomas in children are similar to those in adults. The results of the study attest to the origin of hepatoblastoma from a pluripotent source.     

Mixed hepatoblastoma in the adult: case report and review of the literature.

A case of mixed hepatoblastoma in a woman is described. A survey of the English literature reveals 13 cases acceptable as mixed hepatoblastoma; these have been described and published under a variety of names. Difficulties in nomenclature and the histology of these cases are discussed. Diagnosis depends on the identification of both malignant mesenchymal and malignant epithelial elements. The former include myxoid connective tissue resembling primitive mesenchyme and areas resembling adult fibrosarcoma. Mature fibrous tissue with calcification and bone formation may be seen. Epithelial areas show tissue resembling fetal liver, poorly differentiated epithelial cells, and/or areas of adenocarcinoma. The current view on histogenesis is also given.     

Ovarian serous cystadenoma associated with Sertoli-Leydig cell tumor--a case report.

We Describe a case of ovarian serous cystadenoma having Sertoli-Leydig cell tumor, well differentiated, in the cystic septum. Well differentiated Sertoli-Leydig cell tumor coexisting with other tumor, including serous tumor, has not yet been described. In all cases of Sertoli-Leydig cell tumor with heterologous components or other tumors, the androblastomatous components are intermediately or poorly differentiated. The present case revealed a well differentiated Sertoli-Leydig cell tumor arising in a septum of serous cystadenoma, as a circumscribed nodule. With these findings, we discuss the possibility of this Sertoli-Leydig cell tumor, considered a mural nodule, which is well established in cystic common epithelial tumors of the ovary.     

A novel monoclonal antibody identified hepatic stem-like cells in rats

Both liver epithelial and oval cells are believed to be liver stem cells. We investigated the identification by producing monoclonal antibodies against liver epithelial cells. Monoclonal antibodies against hepatic stem-like cells (HSL cells) have been selected to follow the hepatic stem cells during hepatic regeneration and developmental changes in the liver. Monoclonal antibodies were induced by immunization of BALB/c mice with HSL cells established from the epithelial cells of the adult rat liver. The hybridomas were screened by indirect immunofluorescence staining of HSL cells. We produced a unique monoclonal antibody against HSL cells, MabH, which specifically recognizes liver epithelial cells. MabH did not react with liver parenchymal cells but did react with bile ductule cells under normal conditions in the adult liver. This antibody also reacted with oval cell lines and with the oval cells that appeared during liver regeneration. In addition, fetal liver cells showed immunoreactivity with MabH. Although the level of staining decreased after birth, some cells in the portal area remained highly reactive. These results suggested that liver epithelial cells, oval cells, and fetal liver cells possess a common cell marker of liver stem cells.     

Hepatoblastoma in a 15-month-old male: cytomorphology, electron microscopy, and differential diagnosis

The authors describe a case of hepatoblastoma in a 15-month-old male and discuss the differential diagnosis and electron microscopic features of small round cell tumors. The patient was found to have an enlarged liver and was admitted to the hospital for further investigation. Fine-needle aspiration of the liver revealed small, uniform cells with increased nuclear/cytoplasmic ratio and focal rosette formation. A diagnosis of small blue cell neoplasm favoring hepatoblastoma was made, but neuroblastoma could not be ruled out. Electron microscopic analysis performed on the liver aspirate showed features of hepatic differentiation as well as absence of neuroblastic differentiation. The diagnosis of hepatoblastoma was made. Serum alpha-fetoprotein level of 33,250 mg/L confirmed the diagnosis. Liver biopsy performed subsequently showed tumor cells arranged in nests, acini, and trabeculae with mitotic figures. Electron microscopy showed the same findings as described above. The patient underwent chemotherapy for 4 months and subsequently a partial liver resection was performed. This case illustrates the important role of electron microscopy in evaluating small round cell tumors in children.