Ultrastructure of liver cell and bile duct carcinomas

A Light Microscopic and Ultrastructural Study of Two Cases of Fibrolamellar Hepatocellular Carcinoma

We describe two cases of fibrolamellar hepatocellular carcinoma of the liver in two young women. Both patients presented with diffuse intra-abdominal metastases; nevertheless they had a survival of 28 and 32 months, respectively, which sustains the better prognosis of this neoplasm. Electron microscopy of one case confirmed the oncocytic features of the neoplastic cells and showed intra- and intercellular duct-like vacuoles with numerous microvilli containing a microfilament core that terminated in a terminal web, which represents an unusual aspect in the spectrum of differentiation of fibrolamellar hepatocellular carcinoma.

A Light Microscopic and Ultrastructural Study of Spindle-Shaped Hepatocellular Carcinoma

Spindle-cell hepatocellular carcinoma is an unusual morphologic variant of hepatocellular carcinoma with a typical sarcomatous appearance. The exact diagnosis of this tumor may be difficult when only small biopsies are available and in the absence of ultrastructural studies. We describe two cases of hepatocellular carcinoma: one was entirely composed of spindle-shaped cells, and the other was a typical hepatocellular carcinoma with only a small area of sarcomatous, fusiform cells. In the first case, ultrastructural studies demonstrated desmosomes and many Mallory bodies and confirmed the epithelial nature of the neoplasm. In the second case, no ultrastructural studies were available, but the presence of gradual transition from liver cell carcinoma to spindle-cell carcinoma excludede the diagnosis of carcino-sarcoma.

Combined hepatocellular and cholangiocellular carcinoma in a dog

A transitional type of combined hepatocellular and cholangiocellular carcinoma developed in a 12-year-old male Yorkshire terrier dog. The tumor was histologically composed of both hepatocellular carcinoma and cholangiocellular carcinoma components, and both elements were closely intermingled. Intraluminal mucin accumulation in cytokeratin-positive tubular/glandular structures was observed within the cholangiocellular carcinoma components and this feature was useful histological marker for a differential diagnosis between combined hepatocellular and cholangiocellular carcinoma and a pseudoglandular type of hepatocellular carcinoma. This primary hepatic tumor is extremely rare in dogs.

Electron microscopy in tumor diagnosis: indications for its use in the immunohistochemical era

The electron microscope reveals much more information on tumor cell structure than can be obtained with the light microscope, and some of the data are useful in diagnostic studies. In this review, major contributions of electron microscopy in the main tumor categories are discussed. To select between immunocytochemistry and electron microscopy, the probable contributions of each in the context of the particular case must be assessed. Usually, electron microscopy will only be requested after a battery of immunostaining procedures has been performed and found to be insufficient, but there are occasions when ulstrastructural study is logically the first choice after routine light microscopy. It is worth taking tissue for possible electron microscopy from any tumor that is known or anticipated to be a diagnostic problem.

Cytology: screening or diagnostic tool?

Previously used only as a screening tool, cytology now emerges as a powerful diagnostic technique, especially since the advent of the fine needle aspiration (FNA) biopsy. This article highlights the use of ancillary techniques, primarily electron microscopy (EM), and immunohistochemistry (IHC). When coupled with routine cytological examination such as FNA and body cavity fluid cytology, EM and IHC can refine the diagnosis and make it more precise. The authors discuss how to solve common diagnostic dilemmas by the use of cytology along with IHC and EM. The following common diagnostic problems are addressed: mesothelioma versus adenocarcinoma, neuroendocrine neoplasms and their mimickers, melanoma versus carcinoma versus sarcoma, hepatocellular carcinoma versus adenocarcinoma and adenocarcinomas of unknown primary.

Alveolar soft-part sarcoma: a review of the pathology and histogenesis

The descriptive designation, alveolar soft-part sarcoma, continues to be used for this uncommon soft-tissue malignancy because an acceptable hypothesis for its histogenesis has not been advanced, despite studies with electron microscopy and immunohistochemistry. These techniques have, nevertheless, provided significant information that is useful in the differential diagnosis of the tumor and pertinent in speculation concerning its nature. The most intriguing ultrastructural feature is the secretory process that culminates in the formation of the distinctive cytoplasmic crystals. Myogenic differentiation has been favored in a number of recent reports on the basis of immunohistochemical findings and the presence of the crystals does not rule out the possibility, but accounts of immunoreactivity for the myogenic regulatory protein MyoD1 have not been confirmed in subsequent studies or in the authors' own staining of six cases.

Clear cell papillary carcinoma of the liver: an unusual variant of peripheral cholangiocarcinoma

Cholangiocarcinomas may be extrahepatic or intrahepatic; the latter are further divided into hilar and peripheral types. Peripheral cholangiocarcinomas often resemble adenocarcinomas arising in other organs. Although clear cell changes may occur in hepatocellular carcinoma and extrahepatic cholangiocarcinoma, peripheral cholangiocarcinomas with clear cell change are rare. In such cases, an extrahepatic primary carcinoma must be excluded. We present a patient with a large, clear cell papillary carcinoma in the liver. Extensive workup of the patient for other possible primary sites including kidneys, adrenals, thyroid, prostate, or urinary bladder failed to indicate any other neoplasm. The patient is alive without evidence of disease 30 months after complete resection. The histological, immunohistochemical, and electron microscopic results were most consistent with a neoplasm in the cholangiocarcinoma family. To the best of our knowledge, a clear cell papillary peripheral cholangio carcinoma has not been described previously. This neoplasm may be related to the recently described clear cell carcinomas of the gallbladder and extrahepatic bile ducts.

Hepatic neoformations

The aim of the paper is an accurate histologic description and illustration of those liver lesions that are usually summarized under the heading of "hepatic tumors and related subjects". For in some cases it may be unclear or at least controversial, whether the individual lesion is indeed an autonomous neoplasia or a malformation, regeneration or hyperplasia, the indifferent master term of neoformation is introduced, based on the fact that all of them are characterized by a cellular multiplication. According to common definitory practice the survey distinguishes between mesenchymal (angiomatous and non angiomatous) and epithelial neoformations. Among the latter hepatocellular and cholangiocellular types are distinguished, the criterium for differentiation being a phenomenological one, which is by no means identical with a histogenetical statement. The definition of subgroups mostly adheres to current nomenclatory usage; only occasionally--in the group of endothelial tumors--a novel term is employed, in view of brevity and coordination with the overall system of neoformations.

Light and electron microscopic analysis of liver sinusoids during hepatocarcinogenesis with 2-acetylaminofluorene in rats

To clarify the sequential changes and morphological differences of the sinusoidal structures between hepatocellular carcinoma (HCC) and hepatocellular adenoma (HA), we examined morphological changes of sinusoidal cells and related structures such as basement membrane during hepatocarcinogenesis in the rat. During continuous feeding of carcinogenic diets containing 2-acetylaminofluorene to rats, HA appeared at the 8th week in the peripheral area and then extended toward the centrolobular area. The appearance of HCC was recognized at the 27th week. In the HA lesion, the morphology of sinusoidal cells and related structures was basically the same as that of normal liver except for a slight thickening of the basement membrane and a decreased amount of vitamin A-lipid droplets of stellate cells. In HCC, the fenestrations of endothelial cells disappeared and the basement membrane became continuous, thick and often multilayered. Stellate cells contained almost no vitamin A-lipid droplets and were associated with abundant collagen fibers. Kupffer cells and pit cells were not seen inside the sinusoid. All these features of the sinusoids in HCC resembled the morphological characteristics of the capillary. The present study has revealed that HCC possesses sinusoid structures distinct from those of HA. This suggests that HCC may not derive directly from HA but may develop newly within the HA.

Ultrastructure of adrenal cortical carcinoma

The ultrastructural features of 30 adrenal cortical carcinomas have been reviewed and compared with those seen in adrenal cortical adenomas, adrenal cortical hyperplasia, and the normal cortex. A broad range of ultrastructural appearances was found among the carcinomas, but the differences were mainly in the amount of cytoplasmic lipid, number of lysosomes, and quantity and architecture of the mitochondria and endoplasmic reticulum. Structural variants among the carcinomas included lipid-rich, oncocytic, and glycogen-rich cells. Electron microscopy can be extremely useful in differential diagnoses that include adrenal cortical carcinoma.

Hepatoblastomas: an ultrastructural and immunohistochemical study

Seven hepatoblastomas were studied by electron microscopy, and four of these were studied by immunohistochemistry. Five tumors were purely epithelial, and two were mixed epithelial-mesenchymal. They showed a spectrum of cellular differentiation ranging from primitive epithelial cells to differentiated cells resembling adult hepatocytes. Glycogen, lipid, basal lamina, and canaliculi were present in all cases. Mitochondria with large, membrane-bound, amorphous inclusions were present in one tumor, and large, complex, basal cell processes were present in two tumors. Ultrastructural features most characteristic of hepatocytes were most common in fetal type hepatoblastomas. Immunoreactive chromogranin cells were present in two tumors, one of which also contained immunoreactive somatostatin cells. The somatostatin-positive tumor had cells with granules resembling those seen in somatostatin-containing cells of normal pancreas and somatostatin-containing neuroendocrine carcinomas. Other immunoreactive substances were present, including alpha 1-antitrypsin (four cases), vimentin (embryonal cells in four cases; fetal cells in three cases), low-molecular weight cytokeratin (embryonal cells in three cases; fetal cells in four cases), and high-molecular weight cytokeratin (embryonal cells in one case; fetal cells in two cases). Osteoidlike material was positive for epithelial membrane antigen, vimentin, and S-100 protein.

Well-differentiated hepatocellular carcinoma associated with long-term survival. Report of two cases

Two cases of well-differentiated hepatocellular carcinoma (HCC) with focal biliary differentiation are presented. The distinct histological features of these neoplasms and the unusually protracted clinical course of 8 and 10 years distinguish them from previously described pathological categories of primary hepatic tumors. Electron microscopic and immunohistochemical findings support a dual hepatic and bile duct differentiation of the tumor cells. If additional examples of this tumor are found to be associated with a similarly prolonged symptom-free survival, the distinction of this entity from traditional, rapidly fatal HCC becomes important. Less aggressive therapeutic options may be entertained.

Oncocytic adrenal cortical carcinoma

A case of adrenal cortical carcinoma composed of mitochondria-rich cells is reported. The cells contained condensed zones and loose whorls of smooth endoplasmic reticulum. Crystalline matrical inclusions were present in some of the mitochondria, whereas others contained round, homogeneous, dense matrical inclusions. Flow cytometry revealed a hyperdiploid stem line with a DNA index of 1.3.

Synovial sarcoma: an immunohistochemical and ultrastructural study

Thirty-nine primary synovial sarcomas (15 biphasic, 24 monophasic), and 19 metastatic synovial sarcomas were studied with a battery of antibodies directed to keratin, epithelial membrane antigen (EMA), carcinoembryonic antigen (CEA), vimentin, desmin, muscle-specific actin, smooth muscle actin, S-100 protein, Leu-7, chromogranin A, laminin, collagen IV, Ulex europaeus agglutinin I (UEAI), and the HMB-45 antimelanoma antibody. Twenty-two primary and 18 metastatic synovial sarcomas were also examined by electron microscopy. Epithelial and/or spindle cells in every biphasic tumor, primary and metastatic, reacted for keratin and EMA, but only six primary tumors (five biphasic and one monophasic) showed weak reactivity for CEA which, in the biphasic tumors, was confined to the epithelial component. Of the monophasic tumors, 15 primary (63%) and four metastatic (25%) stained for keratin, whereas seven primary (29%) and two metastatic (13%) tumors reacted for EMA. Only one primary monophasic synovial sarcoma stained for CEA. Tumors that stained for EMA or CEA also stained for keratin which is, therefore, the most useful epithelial marker. Immunostaining for epithelial markers, UEAI, collagen IV, and laminin serves to delineate the epithelial component when it is obscure in routine sections. Electron microscopy facilitates the diagnosis when epithelial markers are not expressed and aids in separating monophasic synovial sarcomas from other sarcomas that they resemble by light microscopy.

An immunohistochemical and ultrastructural study of the sinusoids of hepatocellular carcinoma

The sinusoids of 30 human hepatocellular carcinomas of various types were examined by electron microscopy and histochemically for binding to the Ulex europaeus lectin (UEA1). A population of sinusoidal macrophages was identified with an antibody to lysozyme (muramidase). The UEA1 binding was negative in normal sinusoids but positive in the tumor vessels. Macrophages resembling Kupffer cells were found within the tumor vessels but in smaller numbers than in either normal or cirrhotic liver tissue. Fibrolamellar and sclerosing carcinomas contained the smallest numbers. Ultrastructurally, endothelial cells of tumor vessels were thicker than normal, with fewer fenestrations. They contained bundles of microfilaments and showed basement membrane formation. Subendothelial myoid cells were found. These findings indicate that the sinusoidal vessels of hepatocellular carcinomas show features of true capillaries and precapillary blood vessels. The degree of this difference from normal hepatic sinusoids may reflect the relative immaturity of the cancer cells.

A clinicopathologic study of primary hepatic carcinoid tumors

Six cases of primary hepatic carcinoid tumors were studied with combined immunocytochemical and electron microscopic techniques. Positive tumor immunostaining with PHE5, LK2H10, neuron-specific enolase (NSE), serotonin, gastrin, and insulin antibodies was observed. At the ultrastructural level, cytoplasmic dense granules were seen in all the cases tested. This finding supports a putative origin of these carcinoids found in the liver from a pluripotential stem cell. The clinical course and follow-up of these cases suggests that this unusual hepatic neoplasm has a more favorable prognosis than other forms of hepatic cancer.

Mouse hepatoblastomas: a histologic, ultrastructural, and immunohistochemical study

Hepatoblastomas from B6C3F1 and BALB/c mice were examined by light and electron microscopy and by immunohistochemical reactions for alpha-fetoprotein, keratin, and vimentin. Tumors occurred in one group of a chronic bioassay for the interaction of diet, genetic strain, and the carcinogen, 2-acetylaminofluorene. Tumors had several populations (including epithelial and mesenchymal cells) in various stages of differentiation. Neoplastic epithelial cells had features of embryonal hepatocytes, such as sparse cytoplasmic organelles, absence of glycogen, abundant free ribosomes, occasional bile canaliculi, and peroxisome-like dense bodies. Embryonal fibroblast-like cells had pleomorphic and folded nuclei with prominent perinuclear chromatin and dispersed cytoplasmic organelles. Fibroblast-like cells were surrounded by bundles of collagen fibrils. Intermediate or transitional types of cells were seen. No tumor cells were immunoreactive for mouse alpha-fetoprotein (AFP) antibody, unlike those in hepatocellular adenomas or carcinomas. Epithelial and mesenchymal tumor cells contained intermediate filaments throughout the cytoplasm; some of these cells stained for keratin but not for vimentin. These findings suggest that mouse hepatoblastomas are derived from bipotential liver blastema cells and are composed of a mixture of several cell populations.

Fine-needle aspiration cytology of pediatric patients with primary hepatic tumors: a comparative study of two hepatoblastomas and a liver-cell carcinoma

The cytologic features of fine-needle aspirates (FNA) of two hepatoblastomas (HBs) and a liver-cell carcinoma (LCC) occurring in three children, ages 1, 3, and 14 yr, are presented. Electron microscopic features of one of the HBs and the LCC are also included. The HBs displayed single or small aggregates or larger clusters of cells with a high nuclear-cytoplasmic ratio and usually round, hyperchromatic nuclei with single, and occasionally double, prominent nucleoli. In addition, one patient had extramedullary hematopoiesis; both had osteoid-like material. These findings were very helpful in differentiating the HB cases from the LCC case, which had features similar to those of adult hepatocytes, including the presence of abundant, finely granular cytoplasm. Ultrastructural studies showed an absence of differentiation into adult hepatocytes in the HB, with scant organelles, rare bile canaliculi, lakes of glycogen, and rare lysosomal bodies. In contrast, the LCC showed features similar to adult hepatocytes, such as abundant cytoplasmic organelles, lysosomes, and bile canaliculi. In addition, intranuclear pseudoinclusions caused by cytoplasmic invagination were present in the LCC but not in the HB. Fine-needle aspiration of hepatic masses in children is a useful technique for rendering a diagnosis, especially in unresectable tumors. Ultrastructural studies on FNA material may be important in differentiating hepatoblastoma from hepatocellular carcinoma.

Cellular junctions in a spectrum of human malignant tumors

Cellular junctions in tumors are often considered a hallmark of epithelial differentiation. However, junctions are also seen in tumors having a different differentiation. This observation prompted us to study cellular junctions in malignant nonepithelial tumors. We found a variety of cellular junctions in such tumors, although the majority were poorly formed. This observation is of importance for diagnostic purposes. We have also tried to clarify the nomenclature of cellular junctions as applied in tumor diagnosis by proposing a systematic categorization of terms in everyday use by pathologists and by referring more extensively to the term paired subplasmalemmal densities (PSD) for non-well-formed junctions.

Hepatoblastoma: an immunohistochemical and ultrastructural study

The ultrastructural and immunohistochemical features of 19 hepatoblastomas were examined to evaluate the phenotypic expressivity of this solid embryonic neoplasm of childhood. Electron microscopy confirmed the embryonal and fetal characteristics of the neoplastic hepatocytes, but in addition, cells with features intermediate between these two cell types were identified. Dense bundles of collagen corresponding to the osteoid-like material by light microscopy surrounded nests of cells; the cells within this matrix stained for epithelial membrane antigen and vimentin and focally for cytokeratin, and they showed ultrastructural features of epithelial cells. The two cases of small cell hepatoblastoma reacted positively for vimentin and cytokeratin; the remaining 17 cases were immunoreactive for cytokeratin and alpha-fetoprotein, and some also for alpha 1-antitrypsin, ferritin, and vimentin. A histogenetic scheme based on our findings is proposed to explain the divergent morphologic features of this neoplasm.

Concentric membranous bodies in hepatocytes from a patient with systemic lupus erythematosus

Concentric membranous bodies (CMB) are described in the cytoplasm of hepatocytes in a liver biopsy from a patient with systemic lupus erythematosus (SLE). Histologically, the biopsy showed binucleated hepatocytes and rosette formation with lymphocytic infiltrates in portal fields. Hepatocyte cytoplasm showed focal fatty metamorphosis, focal staining for RNA with azure B at pH 4.0 (which was perchloric acid labile), diffuse alloxan-Schiff staining for protein, and PAS-positive, diastase-sensitive glycogen. By electron microscopy one to three CMB were present in 10-15% of hepatocytes. CMB appeared as concentric, "fingerprint" or parallel arrays of particle-studded, membranous profiles. Other membranous configurations included mazelike forms. The space of Disse was dilated. Bile ductular changes included basement membrane thickening and redoubling and luminal bulging of ductular epithelium devoid of microvilli. CMB have been rarely reported in human hepatoma and have not heretofore been observed in non-neoplastic human liver. Their appearance in hepatocytes in a patient with SLE may reflect an increase in protein synthesis during regeneration.

Primitive cystic hepatic neoplasm of infancy with mesothelial differentiation: report of a case

A malignant cystic neoplasm in the liver of a 6-month-old girl is reported. The neoplasm has unique clinical and morphological features, and despite ultrastructural and immunohistochemical studies, the tumor could not be clearly classified as any known primary hepatic neoplasm of infancy. A differentiated cystic component of the neoplasm had features of cystic peritoneal mesothelioma. Alpha-1-antitrypsin and alpha-fetoprotein were demonstrated in solid, anaplastic portions of the recurrent tumor by immunohistochemistry. The neoplasm recurred after surgical resection and proved fatal 11 months following diagnosis, despite multiple courses of chemotherapy.