The effect of idebenone, a coenzyme Q analogue, on hydrophobic bile acid toxicity to isolated rat hepatocytes and hepatic mitochondria.

Oxidant stress induced by hydrophobic bile acids has been implicated in the pathogenesis of liver injury in cholestatic liver disorders. We evaluated the effect of idebenone, a coenzyme Q analogue, on taurochenodeoxycholic acid (TCDC)-induced cell injury and oxidant stress in isolated rat hepatocytes and on glycochenodeoxycholic acid (GCDC)-induced generation of hydroperoxides in fresh hepatic mitochondria. Isolated rat hepatocytes in suspension under 9% oxygen atmosphere were preincubated with 0, 50, and 100 micromol/l idebenone for 30 min and then exposed to 1000 micromol/l TCDC for 4 h. LDH release (cell injury) and thiobarbituric acid reactive substances (measure of lipid peroxidation) increased after TCDC exposure but were markedly suppressed by idebenone pretreatment. In a second set of experiments, the addition of 100 micromol/l idebenone up to 3 h after hepatocytes were exposed to 1000 micromol/l TCDC resulted in abrogation of subsequent cell injury and markedly reduced oxidant damage to hepatocytes. Chenodeoxycholic acid concentrations increased to 5.15 nmol/10(6) cells after 2 h and to 7.05 after 4 h of incubation of hepatocytes with 1000 micromol/l TCDC, and did not differ in the presence of idebenone. In freshly isolated rat hepatic mitochondria, when respiration was stimulated by succinate, 10 micromol/l idebenone abrogated the generation of hydroperoxides during a 90-minute exposure to 400 micromol/l GCDC. These data demonstrate that idebenone functions as a potent protective hepatocyte antioxidant during hydrophobic bile acid toxicity, perhaps by reducing generation of oxygen free radicals in mitochondria.

Renal neoplasms mimicking rhabdoid tumor of kidney. A report from the National Wilms' Tumor Study Pathology Center.

Fifty-six renal neoplasms reviewed by the National Wilms' Tumor Study Pathology Center presented with histologic features that resulted in confusion with rhabdoid tumor of kidney, a usually lethal childhood renal tumor; all were eventually diagnosed as other entities. Conspicuous filamentous cytoplasmic inclusions or large nucleoli, typical findings in rhabdoid renal tumors, were the usual source of diagnostic difficulty. Most, but not all, tumors occurred in pediatric patients. Sixteen were examples of Favorable Histology Wilms' tumor, which invited confusion with rhabdoid tumors either on the basis of filamentous cytoplasmic inclusions (15 cases) or macronucleoli (one case). In most cases, foci of typical Wilms' tumor blastemal aggregation or evidence of definitive nephrogenic differentiation facilitated the correct diagnosis. All 10 patients for whom information about outcome was available were alive at last follow-up. The other 40 renal lesions mimicking rhabdoid tumor of kidney consisted of a clinically and histogenetically diverse group of neoplasms, including anaplastic Wilms' tumor, congenital mesoblastic nephroma, renal cell carcinoma, transitional cell carcinoma, collecting-duct carcinoma, oncocytoma, rhabdomyosarcoma, malignant neuroepithelial tumors, and lymphoma. Most of these lesions could be separated from renal rhabdoid tumors and correctly classified on the basis of careful attention to light microscopic details, but in several cases electron microscopy or immunocytochemical studies were helpful or essential.

Rhabdoid tumor of kidney. A report of 111 cases from the National Wilms' Tumor Study Pathology Center.

We review 111 cases of rhabdoid tumor of kidney (RTK), including 79 entered on the National Wilms' Tumor Study (NWTS). Median age at diagnosis was 11 months, with a range from 0 to 106 months. The male:female ratio was 1.5:1. Gross features included a characteristic involvement of perihilar renal parenchyma. A wide histological spectrum was encountered, including nine major morphological patterns (classical, epithelioid, sclerosing, lymphomatoid, histiocytoid, etc.). These appearances invite confusion with other renal neoplasms. Ultrastructural studies were performed in 20 cases; immunocytochemical studies were performed in 11. Vimentin was demonstrated in all tumors; epithelial membrane antigen was seen in 7. Nonspecific decoration of cytoplasmic inclusions by a variety of immunostains was found in several cases. Several findings suggested that RTK might arise from primitive cells involved in formation of the renal medulla. There was no evidence of a histogenetic relationship to Wilms' tumor, although RTK may overlap with mesoblastic nephroma and clear cell sarcoma. Of the 70 NWTS patients with adequate follow-up, 56 (80%) have died. Every patient presenting with distant metastases died, whereas 10 of 20 with negative nodes survived. Survival rates were higher for girls (56.3% versus 11.1%). None of the histological variables had independent prognostic significance.

Oncocytic adrenocortical neoplasms: a report of seven cases and review of the literature.

Oncocytic neoplasms of the adrenal gland are rare. We describe the clinicopathologic and immunohistochemical findings of seven oncocytic adrenocortical neoplasms, five oncocytomas, and two oncocytic neoplasms of uncertain malignant potential. Three tumors were studied using electron microscopy. These neoplasms occurred in five women and two men (median age, 55 years) with no clinical evidence that the neoplasms were functional. The size of the neoplasms varied from 5.0 cm to 13.5 cm. Histologically, each neoplasm was composed exclusively of oncocytes. The oncocytomas had very low or absent mitotic activity and no evidence of necrosis. The two oncocytic neoplasms of uncertain malignant potential had increased mitotic activity and necrosis but no evidence of invasion or metastases. Nuclear atypia, either focal or generalized, was found in all neoplasms. Immunohistochemical studies performed using fixed, paraffin-embedded sections showed strong reactivity with the mitochondrial antibody mES-13 in all neoplasms. Four of five oncocytomas and one oncocytic neoplasm of uncertain malignant potential expressed keratin, predominantly keratin 18, as shown using the CAM 5.2 and AE3 antibodies. Two neuroendocrine-associated markers, neuron specific enolase and synaptophysin, were positive in seven and five neoplasms, respectively. However, all neoplasms were negative for the other neuroendocrine markers tested, including chromogranin A, tyrosine hydroxylase, and dopamine beta-hydroxylase, as well as for epithelial membrane antigen, S100, and p53. Using the MIB-1 (Ki-67) antibody, proliferative activity was increased in both oncocytic neoplasms of uncertain malignant potential. All six patients with available clinical follow-up data are alive without evidence disease, although the follow-up interval is relatively short (< 2 years) for the two patients with oncocytic neoplasms of uncertain malignant potential. We conclude that oncocytic adrenocortical neoplasms are nonfunctional tumors that can become large before they are detected by radiologic studies. The majority of neoplasms are benign and should not be misdiagnosed as carcinoma.

Histiocytosis X.

To clarify salient issues pertaining to histiocytosis X--a syndrome that includes Letterer-Siwe disease, Hand-Schuller-Christian disease, and eosinophilic granuloma--the authors review the epidemiologic data and the histologic, morphologic, and clinical bases for diagnosis and prognosis. Histiocytes are defined and their possible histogenesis outlined, and Langerhans cells, which may be a leading element in active lesions, are characterized. The authors outline hypothetic pathogenetic schema, which they recommend be tested by recently developed immunologic and genetic means, since histiocytosis X, at least in its disseminated form, remains an unpredictable disease for which there is no proven effective therapy.

Benign nodal lesions mimicking metastases from pediatric renal neoplasms: a report of the National Wilms' Tumor Study Pathology Center.

Regional lymph node status is a key factor in the staging of pediatric renal tumors on the National Wilms' Tumor Study (NWTS). A review of cases entered on the NWTS has uncovered a number of cases where benign lymph node findings were mistaken for metastases. Most frequently, this was due to the presence of complexes of epithelial cells and Tamm-Horsfall protein within nodal sinuses. The epithelial cells were derived from damaged nephrons, usually resulting from obstruction by tumor. Another epithelial pseudometastic lesion, intranodal squamous epithelial cells, was found to originate from metaplastic calyceal urothelium. Benign mesothelial or coelomic inclusions similar to those previously described in pelvic and periaortic lymph nodes of adult females were found in nodes of four patients, including two boys, who are, to our knowledge, the first to be described with this finding. Other sources of confusion included protrusion of lymphoid follicles or germinal centers into nodal sinuses, thick endothelial cells of postcapillary venules mimicking epithelial tubules, nodal megakaryocytes resembling anaplastic nuclear changes, and histiocytic granulomas. Immunocytochemical methods were useful in evaluating some of these phenomena. Recognition of these pseudometastatic lesions is essential in order to avoid unnecessary and potentially hazardous therapeutic intensification.

Role of electron microscopy and other special techniques in the diagnosis of childhood round cell tumors.

A series of case presentations show unique challenges associated with childhood round cell tumors and the role of ancillary techniques in diagnosis. Electron microscopy is shown to be the most powerful individual technique. Immunohistochemistry is less effective but also essential. Other ancillary techniques may provide needed additional diagnostic information. Because this is an area where it is of great importance to secure the most rapid, accurate, and specific diagnosis possible, an integrated multimodal approach is recommended--incorporating light microscopic, electron microscopic, and immunohistochemical studies as a matter of routine, and providing for cytogenetic and/or molecular diagnostic studies as indicated.

Unusual dural and skull-based mesenchymal neoplasms: a report of four cases.

Dural and skull-base mesenchymal neoplasms other than meningiomas are rare. We report four such tumors, some of which are uncommon even in nonintracranial sites, in three adults and one child. The adult tumors consisted of a synovial sarcoma of the third ventricle region in a 19-year-old woman, a leiomyoma of the suprasellar region in a 57-year-old woman, and an Epstein-Barr virus (EBV)-associated smooth muscle tumor of the cavernous sinus in a 35-year-old woman with acquired immunodeficiency syndrome (AIDS). The pediatric tumor was an EBV-associated leiomyosarcoma of the left dural transverse sinus in a 14-year-old girl with common variable immunodeficiency syndrome. All tumors were thought to be primary in their dural or skull-base locations. The two EBV-associated smooth muscle tumors in immunocompromised patients expand the locations for EBV-associated smooth muscle tumors to dural and skull-base sites, the synovial sarcoma is unique to the intracranial space, and the sellar leiomyoma represents the third reported sellar smooth muscle tumor.

Conjunctival biopsy in infantile neuroaxonal dystrophy.

PURPOSE: To describe a case of infantile neuroaxonal dystrophy with optic nerve atrophy and to discuss the diagnostic role of conjunctival biopsy. METHODS: We performed a complete ophthalmologic examination and a diagnostic conjunctival biopsy on a girl with a neurodegenerative disease. RESULTS: On the basis of "spheroid" inclusions in the unmyelinated axons, we diagnosed infantile neuoroaxonal dystrophy. CONCLUSIONS: Optic atrophy is an important finding in infantile neuroaxonal dystrophy, and conjunctival biopsy is a reliable and very convenient diagnostic test.

Rhabdoid glioblastoma.

Rhabdoid phenotypic change has been described in a number of different neoplasms from diverse organ sites. These tumors share common light and electron-microscopic features, display a polyphenotypic immunohistochemical profile and often show cytogenetic abnormalities of chromosome 22. In the central nervous system (CNS), most rhabdoid tumors occur in the posterior fossa of very young children and are associated with a primitive neuroectodermal tumor (PNET) component and are designated atypical teratoid/rhabdoid tumors. Infrequently, other rhabdoid tumors of the CNS have been described, including rhabdoid meningiomas and malignant rhabdoid tumors of uncertain histogenesis. Several examples of conventional gliomas displaying significant areas with rhabdoid morphology were also presented in an abstract by Kepes and Moral [1991], although never published in final manuscript form. We now detail the case of an 18-year-old male with an aggressive, supratentorial CNS rhabdoid tumor that was associated with an epithelioid glioblastoma and apparently arose from areas of low-grade glioma. The rhabdoid tumor component was present in the original tumor but became more predominant with each of 3 successive resections. No areas of PNET were identified. Electron microscopy and immunohistochemistry showed features classic for rhabdoid tumors and cytogenetic studies demonstrated multiple tumor clones with monosomy 22. This case documents progressive rhabdoid transformation of a glioma, expands the spectrum of CNS tumor types that can display a rhabdoid phenotype and highlights the diagnostic and therapeutic challenges with this type of tumor.

Amylopectinosis disease isolated to the heart with normal glycogen branching enzyme activity and gene sequence.

We report a 17-month-old female patient with a rare cause of cardiomyopathy secondary to accumulation of amylopectin-like material (fibrillar glycogen) isolated to the heart. Evidence of amylopectinosis isolated to cardiac myocytes in this patient was demonstrated by histology and electron microscopy. Glycogen content, glycogen branching enzyme (GBE) activity, as well as phosphofructokinase enzyme activities measured in liver, skeletal muscle, fibroblasts and ex-transplanted heart tissue were all in the normal to lower normal ranges. Normal skeletal muscle and liver tissue histology and GBE activity, normal GBE activity in skin fibroblasts, plus normal GBE gene sequence in this patient exclude the classical branching enzyme deficiency (type IV GSD). We believe that this is an as yet uncharacterized and novel phenotype of GSD associated with cardiomyopathy, in which there is an imbalance in the regulation of glycogen metabolism limited to the heart.

Electron microscopy for tumour diagnosis: is it redundant?

The histopathological diagnosis of tumours has been transformed by immunohistochemistry. Used with experience and judgement, a panel of antibodies or antisera, combined when necessary with antigen retrieval, will enable the accurate typing of most problematic tumours. This has led many histopathologists to question whether the electron microscope has any residual utility for tumour diagnosis; the machines are large, costly to purchase and maintain, and will accept only minute samples of tissue. The following articles by Mierau and by Eyden, both strong advocates, comment on the current and future role of electron microscopy in tumour diagnosis.

An unusual banded structure in Ewing's sarcoma.

In a largely haemorrhagic and necrotic specimen of Ewing's sarcoma we found banded structures (periodicity of banding about 250 nm) of a type hitherto not known to occur in any normal or pathological tissue. Morphological appearances suggested that these structures had evolved from the fibrin which was always closely associated with them. However, this idea was abandoned because the periodicity of banding of these structures is about ten times greater than the known periodicity of banding of fibrin. These structures have the same periodicity of banding as fibrous long-spacing collagen produced in vitro and about twice the periodicity of banding of fibrous long-spacing collagen found in vivo. However, they lack the fine striations or minor bands of the in vitro fibrous long-spacing collagen. We therefore conclude that the banded structures in this tumour represent a new form of fibrous long-spacing collagen which shares the features of in vitro and in vivo types of fibrous long-spacing collagen.

Chondroid chordoma.

We reject the notion that the concept of "chondroid chordoma" be abandoned in favor of an interpretation of the cartilaginous origin of these lesions. We have demonstrated by electron microscopic and immunohistochemical means that these neoplasms can exhibit distinctly epithelial characteristics in their chondroid as well as their epithelial areas. The presence of desmosomes, cytokeratin, carcinoembryonic, and epithelial membrane antigen in the cells of the chondroid as well as the epithelial areas; the presence of the microtubular inclusions, vimentin, and S-100 protein in the cells of the epithelial as well as chondroid areas; and the intermingling of the two and gradual transitions from one to the other all point to the conclusion that the chondroid and epithelial areas are only differing morphologic expressions of the same entity. The gradual evolution witnessed in the sequential biopsies of this case study, through which a predominantly chondromatous neoplasm became a chordoma of typical histologic appearance, provides further strong evidence to support the contention that chondroid chordoma is a variant of chordoma and not a primary chondrocytic neoplasm.

S-100 protein immunohistochemistry and electron microscopy in the diagnosis of Langerhans cell proliferative disorders: a comparative assessment.

To better define the roles of S-100 protein immunohistochemistry and electron microscopy in the diagnosis of Langerhans cell proliferative disorders, a comparative assessment of the two techniques was performed using material from 39 cases of histiocytosis X and 2 cases of infantile self-healing reticulohistiocytoma. Both techniques proved highly reliable, but neither alone enabled diagnostic confirmation in all instances. The two techniques proved complementary and used together did enable identification of Langerhans-type histiocytes in all cases studied. Neither was judged clearly superior and both offered certain advantages. Electron microscopy was found overall to be a slightly less sensitive technique, but more specific and less subject to misinterpretation. The S-100 stain was found to be particularly useful in situations where sampling problems were likely to be encountered or where the available specimen was otherwise suboptimal for electron microscopic examination. Because the S-100 stain is the more cost-effective to employ, we now recommend it for the purpose of providing routine diagnostic confirmation. In an investigative setting, however, we continue to recommend electron microscopy as the primary technique.

Role of electron microscopy in the diagnosis of metabolic storage diseases affecting the nervous system of children.

Metabolic storage diseases are among the most challenging diagnostic problems faced by clinicians and pathologists. There is considerable variation in the diagnostic approach to these diseases between different institutions and between different diagnosticians. Much of this variation arises from differences in the availability of and physician confidence in the diagnostic modalities employed to characterize these disorders. Recent advances in the biochemistry and molecular genetics of these diseases have produced some skepticism about the continued relevance of traditional morphologic techniques, including electron microscopy, in their diagnosis. It is the opinion of the authors that this concern is premature and that electron microscopy continues to play a vital role, particularly in the diagnosis of those entities that challenge the classic definitions of lysosomal storage diseases. The authors present a series of cases illustrating different situations where electron microscopy can provide timely, cost-effective, and accurate information in the workup of such diseases.

Rhabdomyosarcoma in children: ultrastructural study of 31 cases.

Thirty-one cases of rhabdomyosarcoma in children were studied by electron microscopy. All of the tumors examined fit into a continuum of progressive cellular differentiation mimicking that of normal myogenesis, with increasingly differentiated examples being decreasingly common. We conclude that all childhood forms of rhabdomyosarcoma are essentially embryonal tumors, with many not being sufficiently differentiated at the cellular level to allow positive ultrastructural diagnosis.

Small round cell neoplasms: can electron microscopy and immunohistochemical studies accurately classify them?

The answer to the question posed in the title, "Small Round Cell Neoplasms: Can Electron Microscopy and Immunohistochemical Studies Accurately Classify Them?", is obviously "yes"; but a qualified yes--generally yes, perhaps with expertise usually yes, but never just plain yes. Some cases certainly will defy the best attempts even of the most expert in the application of these "special" techniques. And embarrassing as it may be for those of us infatuated with the latest technology to admit, it is with the difficult case especially that old-fashioned technology so often must be depended upon. In his excellent recent appraisal of the role of a variety of special techniques in this application, Triche offers the following comment: "Overall, electron microscopy is probably the most universally useful of all diagnostic techniques other than light microscopy in round cell tumors." The data from our studies certainly point to the same conclusion. With each of the tumors, electron microscopy demonstrated itself to be more reliable than immunohistochemistry. Electron microscopy offers not only greater sensitivity and specificity, but also greater versatility. Immunohistochemistry allows hypothesis testing only. Electron microscopy, on the other hand, can provide answers even when the right questions are not being asked. For example, if a particular small round cell tumor under investigation happens in actuality to represent something other than the neuroblastoma which it is being considered (e.g., a granulocytic sarcoma, liposarcoma, Wilm's tumor, etc.), electron microscopy can reveal this fact, but a neuron-specific enolase stain cannot. Parenthetically, it should also be said that electron microscopy has proven particularly well suited to the examination of fine-needle aspiration specimens. The two spare many patients in our institution the need for a major operative procedure to establish a secure tissue diagnosis. Immunohistochemistry does have a role to play but it is, at least in our opinion, clearly secondary to that of electron microscopy. The concept of replacing electron microscopy with a battery of immunostains has often been advocated as an economic measure, but this argument begins quickly to lose its weight as the number stains included in the battery is increased to cover the diagnostic possibilities. Giving consideration to the capriciousness of some of these stains, there exists with this also an increasing possibility of a spurious or misinterpreted result leading to an errant diagnosis.(ABSTRACT TRUNCATED AT 400 WORDS)

Lipid-rich rhabdomyosarcoma--a potential source of diagnostic confusion.

Rhabdomyosarcoma is an often primitive tumor capable of diverse morphologic manifestations. The article describes three cases of childhood rhabdomyosarcoma in which a significant population of lipid-rich tumor cells was present. The lack of specificity and potentially confusing nature of this feature are discussed, and the ultrastructural diagnosis of rhabdomyosarcoma is briefly reviewed.