Subtracted, unique-sequence, in situ hybridization: experimental and diagnostic applications

Role of Chromogenic in Situ Hybridization (CISH™) in the Evaluation of HER2 Status in Breast Carcinoma: Comparison with Immunohistochemistry and Fish

We report our experience with Chromogenic in Situ Hybridization (CISH™) for the evaluation of HER2 amplification on 55 cases of formalin-fixed, paraffin-embedded invasive breast carcinomas of different histology. All the results were corrected for chromosome 17 aneusomy and compared with immunohistochemistry (IHC); a subset of cases was compared to FISH. Thirty-one of 32 cases in which FISH and CISH™ were performed yielded the same results. CISH™ and IHC showed a good concordance in the 0/1+ and 3+ category, while a poor agreement with weakly protein overexpression was confirmed. Chromosome 17 analysis was necessary in cases with a low number of HER2 gene copies. CISH™ is a useful tool to evaluate breast cancer HER2 status that can be easily implemented in a laboratory of surgical pathology.

AIF downregulation and its interaction with STK3 in renal cell carcinoma

Apoptosis-inducing factor (AIF) plays a crucial role in caspase-independent programmed cell death by triggering chromatin condensation and DNA fragmentation. Therefore, it might be involved in cell homeostasis and tumor development. In this study, we report significant AIF downregulation in the majority of renal cell carcinomas (RCC). In a group of RCC specimens, 84% (43 out of 51) had AIF downregulation by immunohistochemistry stain. Additional 10 kidney tumors, including an oxyphilic adenoma, also had significant AIF downregulation by Northern blot analysis. The mechanisms of the AIF downregulation included both AIF deletion and its promoter methylation. Forced expression of AIF in RCC cell lines induced massive apoptosis. Further analysis revealed that AIF interacted with STK3, a known regulator of apoptosis, and enhanced its phosphorylation at Thr180. These results suggest that AIF downregulation is a common event in kidney tumor development. AIF loss may lead to decreased STK3 activity, defective apoptosis and malignant transformation.

Molecular strategies for detecting chromosomal translocations in soft tissue tumors (review)

Approximately one third of soft tissue tumors are characterized by chromosomal aberrations, in particular, translocations and amplifications, which appear to be highly specific. The identification of fusion transcripts not only supports the diagnosis, but provides the basis for the development of novel therapeutic strategies aimed at blocking the aberrant activity of chimeric proteins. Molecular biology, and in particular, cytogenetic and qualitative and quantitative polymerase chain reaction technologies, allow with high efficiency and specificity, the determination of specific fusion transcripts resulting from chromosomal translocations, as well as the analysis of gene amplifications. In this review, various molecular techniques that allow the identification of translocations and consequent fusion transcripts generated are discussed in the broad spectrum of soft tissue tumors.

Out of the darkness and into the light: bright field in situ hybridisation for delineation of ERBB2 (HER2) status in breast carcinoma

Assessment of ERBB2 (HER2) status in breast carcinomas has become critical in determining response to the humanised monoclonal antibody trastuzumab. The current joint College of American Pathologists and the American Society of Clinical Oncology guidelines for the evaluation of HER2 status in breast carcinoma involve testing by immunohistochemistry and fluorescence in situ hybridisation (FISH). However, neither of these modalities is without limitations. Novel bright field in situ hybridisation techniques continue to provide viable alternatives to FISH testing. While these techniques are not limited to evaluation of the HER2 gene, the extensive number of studies comparing bright field in situ techniques with other methods of assessing HER2 status allow a robust evaluation of this approach. Analysis of the literature demonstrates that, when used to assess HER2 gene status, bright field in situ hybridisation demonstrates excellent concordance with FISH results. The average percentage agreement in an informal analysis of studies comparing HER2 amplification by chromogenic in situ hybridisation with FISH was 96% (SD 4%); kappa coefficients ranged from 0.76 to 1.0. Although a much smaller number of studies are available for review, similar levels of concordance have been reported in studies comparing HER2 amplification by methods employing metallography (silver in situ hybridisation) with FISH. A summary of the advancements in bright field in situ hybridisation, with focus on those techniques with clinical applications of interest to the practicing pathologist, is presented.

Delineation of HER2 gene status in breast carcinoma by silver in situ hybridization is reproducible among laboratories and pathologists

An automated enzyme metallographic silver in situ hybridization method (SISH) has been reported to successfully determine human epidermal growth factor receptor 2 (HER2) gene amplification. We evaluated the staining and interpretative reproducibility of the HER2 SISH assay at five laboratories and compared SISH results with other in situ hybridization (ISH) methods. The HER2 gene status of 89 breast carcinomas was analyzed in parallel using manual dual-color fluorescence ISH, manual chromogenic ISH, and bright-field automated SISH. A total of 1098 SISH-stained slides were evaluated. For comparison, all specimens were stained by 4B5 immunohistochemistry for HER2 protein expression. Interpretation was performed by pathologists at five different laboratories using the algorithms provided by the manufacturers and the guidelines of American Society of Clinical Oncology/College of American Pathologists. Staining and interpretative reproducibility were measured through the computation of weighted kappa statistics. Following the optimization of SISH staining, 1077/1098 (98%) of slides were evaluable. Excellent reproducibility and efficacy of HER2 SISH staining, and interobserver interpretation (Kw = 0.91), were observed among five sites. For the 89 invasive breast cancer cases, the overall rate of concordance between consensus 4B5 and consensus SISH, fluorescence ISH, and chromogenic ISH was 96.6% (86/89), 97.8% (87/89), and 96.6% (86/89), respectively. Overall concordance between positive and negative SISH and fluorescence ISH results, as well as between individual and consensus positive and negative SISH results, was excellent (P < 0.001).

Ewing's sarcoma and peripheral primitive neuroectodermal tumor in adults: different features of a rare neoplasm

INTRODUCTION

In adults, peripheral primitive neuroectodermal tumors (pPNETs) represent a rare and heterogeneous group of neoplasms exhibiting neuronal and glial differentiation.

PATIENTS AND METHODS

We present the clinicopathologic features of four examples of the Ewing's sarcoma (EWS)/pPNET group in adults. Hematoxylin and eosin staining, immunohistochemical and molecular studies were reviewed in every case. Immunohistochemical stains were performed on formalin-fixed, paraffin-embedded sections, molecular studies were done using fluorescence in situ hybridization (FISH).

RESULTS

Three patients presented with tumors of the thoracopulmonary region, one patient showed EWS of the soft tissue. Microscopically, tumor tissue was composed of round, small, blue cells with fine granular chromatin texture and inconspicuous nucleoli. Mitotic figures and rosettes were present. Tumor cells strongly coexpressed CD99 and vimentin, but due to technical reasons t(22q12) translocation studies proved the presumptive diagnosis of EWS/pPNET in one case only. Despite similar multimodality treatment survival time ranged from 6 to 42 months, two patients were alive at the time of reporting.

CONCLUSIONS

As tumors of the EWS/pPNET family behave aggressively, rapid diagnosis is warranted. Since diagnosis of EWS/pPNET requires ancillary studies, it is necessary to consider it even in adult patients.

Leucine-rich repeat C4 protein is involved in nervous tissue development and neurite outgrowth, and induction of glioma cell differentiation

LRRC4, leucine-rich repeat C4 protein, has been identified in human (GenBank accession No. AF196976), mouse (GenBank accession No. DQ177325), rat (GenBank accession No. DQ119102) and bovine (GenBank accession No. DQ164537) with identical domains. In terms of their similarity, the genes encoding LRRC4 in these four mammalian species are orthogs and therefore correspond to the same gene entity. Based on previous research, and using in situ hybridization, we found that LRRC4 had the strongest expression in hippocampal CA1 and CA2, the granule cells of the dentate gyrus region, the mediodoral thalamic nucleus, and cerebella Purkinje cell layers. Using a P19 cell model, we also found that LRRC4 participates in the differentiation of neuron and glia cells. In addition, extracellular proteins containing both an LRR cassette and immunoglobulin domains have been shown to participate in axon guidance. Our data from neurite outgrowth assays indicated that LRRC4 promoted neurite extension of hippocampal neurons, and induced differentiation of glioblastoma U251 cells into astrocyte-like cells, confirmed by morphology observation and glial fibrillary acidic protein expression.

Undifferentiated small round cell sarcomas with rare EWS gene fusions: identification of a novel EWS-SP3 fusion and of additional cases with the EWS-ETV1 and EWS-FEV fusions

Ewing family tumors (EFTs) are prototypical primitive small round blue cell sarcomas arising in bone or extraskeletal soft tissues in children or adolescents. EFTs show fusions of EWS with a gene of the ETS family of transcription factors, either EWS-FLI1 (90 to 95%) or EWS-ERG (5 to 10%). Rare cases with fusions of EWS to other ETS family genes, such as ETV1, E1AF, and FEV, have been identified, but their clinicopathological similarity to classic EFTs remains unclear. We report four new cases of EFT-like tumors with rare EWS fusions, including two with EWS-ETV1, one with EWS-FEV, and a fourth case in which we cloned a novel EWS-SP3 fusion, the first known cancer gene fusion involving a gene of the Sp zinc finger family. Analysis of these three new cases along with data on nine previously reported cases with fusions of EWS to ETV1, E1AF, or FEV suggest a strong predilection for extraskeletal primary sites. EFT-like cases with fusions of EWS to non-ETS translocation partners are also uncommon but involve the same amino-terminal portion of EWS, which in our novel EWS-SP3 fusion is joined to the SP3 zinc-finger DNA-binding domain. As these data further support, these types of EWS fusions are associated with primitive extraskeletal small round cell sarcomas of uncertain lineage arising mainly in the pediatric population.

Expression and functional characterization ofLRRC4, a novel brain-specific member of the LRR superfamily

LRRC4, a novel member of LRR superfamily thought to be involved in development and tumorigenesis of the nervous tissue, has the potential to suppress tumorigenesis and cell proliferation of U251MG cells. This study aimed at revealing the correlation between expression of LRRC4 and the maintenance of normal function and tumorigenesis suppression within the central nervous system. We systematically analyzed the expression and tissue distributions of the gene in tissues. Results showed that LRRC4 expression was limited to normal adult brain, both in human and in mouse, and exhibited a development-regulated pattern, but was down-regulated in brain tumor tissues and U251MG cell line. Furthermore, dynamic alterations in gene expression associated with cell cycle progression were investigated by using Tet-on system. Results showed that LRRC4 induced a cell cycle delay at the late G1 phase, probably through the alteration of the expression of different cell cycle regulating proteins responsible for mediating G1-S progression, such as p21(Waf1/Cip1) and p27(Kip1), Cdk2 and PCNA, p-ERK1/2. These findings suggest that LRRC4 may play an important role in maintaining normal function and suppressing tumorigenesis in the central nervous system.

Testing for HER2 in breast cancer

HER2 is a paradigm of a molecular target whose appropriate assessment is pivotal in the targeting of novel therapies for breast cancer, notably including Herceptin/Trastuzumab. Determining the correct levels requires immunohistochemical and molecular biological skills that are reproducible and measurable, coupled with a knowledge of the appropriate morphological and pathobiological context. Attaining these goals is not easy and laboratories testing for HER2 should maintain a high level of throughput of tests and engage in a recognized external quality assurance scheme. Fluorescence in-situ hybridization testing remains a particular challenge and there is a range of testing strategies. This testing forms the model for the identification of other novel molecular targets. In the future rapid throughput techniques such as real-time quantitative polymerase chain reaction (rqPCR), tissue microarrays or both should bring significant economies of cost and scale.

Carcinoma ex-pleomorphic adenoma of the breast. Report of three cases suggesting a relationship to metaplastic carcinoma of matrix-producing type

Three cases of carcinoma ex-pleomorphic adenoma of the breast are reported. Patients were 82, 60 and 56 years old and presented with a breast lump. All tumours showed areas of pleomorphic adenoma adjacent to typical areas of malignant transformation. These cases add to the spectrum of tumours shared by breast and salivary gland. The relationship between these neoplasms and metaplastic carcinoma of matrix-producing type is discussed.

Chromogenic in situ hybridization analysis of HER-2/neu status in cytological samples of breast carcinoma

The current use of humanized monoclonal antibody trastuzumab for the treatment of patients with metastatic breast cancer has made evaluation of HER-2/neu status an important clinical issue. Chromogenic in situ hybridization (CISH), in which the DNA probe is detected with an immunohistochemistry (IHC)-like peroxidase reaction, has been recently developed for the assessment of HER-2/neu status in formalin-fixed breast cancer specimens. We have applied the technique of dual-colour CISH using HER-2/neu and chromosome 17 centromere probes in 27 cytological smears, and these cytological samples were obtained from scrapings of fresh breast tumours. We also investigated HER-2/neu amplification and protein overexpression in the corresponding surgical tissues by CISH and IHC using the monoclonal antibody CB11. Of the 27 cytological cases, HER-2/neu gene amplification was observed in nine cases that were positive cases (2+ and 3+) for IHC. Among the 13 IHC positive cases (2+ and 3+), four of them showed no gene amplification. Identical results for the CISH technique were obtained in the matched surgical samples. The scrape samples from fresh breast tumour offer a monolayer cell population that is especially suitable for CISH. This study has shown that the cytological smear might be a good alternative for the CISH test.

Interphase fluorescence in situ hybridization for detection of 8q24/MYC breakpoints on routine histologic sections: validation in Burkitt lymphomas from three geographic regions

A chromosomal translocation involving the MYC gene is characteristic of Burkitt lymphoma (BL) and represents a molecular disease marker with diagnostic and clinical implications. The detection of MYC breakpoints is hampered by technical problems, including the distribution of the breakpoints over a very large genomic region of approximately 1,000 kb. In this article, we report on the testing and validation of a segregation fluorescence in situ hybridization (FISH) assay for MYC breakpoints on a large series of BLs. A contig of overlapping genomic clones was generated, and two probe sets flanking the MYC gene were selected. Both probe sets were tested in an interphase FISH segregation assay on 8 B-cell lymphoma cell lines and 32 lymphoma samples with proved 8q24/MYC abnormalities and validated in 47 BLs from The Netherlands, Brazil, and Uganda. MYC translocation breakpoints were identified in 98% of the tumors of the test series and in 89% of the cases of the validation series. In 89% of all positive samples, the breakpoints were located between 190 kb 5' and 50 kb 3' of MYC. Nine cases had more distant breakpoints, and in one patient an insertion of MYC into the IGH region was detected. In two of the three BLs lacking CD10 expression, no breakpoint could be detected, suggesting that CD10 is a discriminative marker of BL. We did not find consistent differences between BL and atypical BL in incidence of an MYC breakpoint.

Detection by the fluorescence in situ hybridization technique of MYC translocations in paraffin-embedded lymphoma biopsy samples

The detection of chromosomal translocations by fluorescence in situ hybridization (FISH) is widely performed, but very few studies have attempted to apply this technique to paraffin-embedded routine biopsy samples. We report the analysis of paraffin sections from 36 B-cell lymphoma biopsies for MYC translocation breakpoints by FISH. The probes consisted of multi-YAC constructs that flanked the breakpoint region and that, therefore, separate upon a chromosomal translocation and generate split (or "segregated") signals (rather than a more ambiguous "co-localization" pattern, obtained when the two partners in a hybrid gene are detected). The results were assessed by a simple approach that avoids the counting of signal numbers per nucleus and so is appropriate for use in routine practice. A total of 19 of the 36 lymphomas were scored as positive for MYC translocation and this included 16 of the 20 patients in whom classic cytogenetics had shown the presence of the (8;14) translocation (or one of its two variants). We conclude that this two-colour "split-signal" technique based on breakpoint flanking probes can readily detect chromosomal translocations in paraffin sections. Furthermore, our results suggest that cases categorized as "atypical Burkitt's/Burkitt-like" lymphoma (at least for adult patients) are heterogeneous with respect to translocations involving the MYC oncogene, as well as immunophenotype and clinical features.

Expression of CEACAM1 in adenocarcinoma of the lung: a factor of independent prognostic significance

PURPOSE

To evaluate the prognostic relevance of CEACAM1 and sialyl Lewis X expression in adenocarcinomas of the lung.

PATIENTS AND METHODS

Paraffin wax sections of 93 patients with adenocarcinomas of the lung who underwent surgery between 1990 and 1995 were immunohistochemically investigated using monoclonal anti-CEACAM1 and sialyl Lewis X antibodies. The clinical course of all patients was followed up for a minimum of 5 years.

RESULTS

Sixty-one tumors were classified as CEACAM1-positive, and 32 were classified as CEACAM1-negative. Patients with CEACAM1-positive tumors had a significantly poorer overall (P =.00025) and relapse-free (P =.00029) survival than those with CEACAM1-negative tumors. Only three patients did not express the sialyl Lewis X glycotope, whereas 90 tumors (97%) were sialyl Lewis X-positive. In multivariate Cox regression analysis, next to tumor stage and sex, only the expression of CEACAM1 was a significant independent prognostic factor for survival.

CONCLUSION

Expression of CEACAM1 was an independent prognostic factor in our patient population and can be used to stratify patients with adenocarcinomas of the lung into low-risk and high-risk groups. In contrast, the expression of sialyl Lewis X was of no prognostic relevance because it was expressed in 97% of all investigated tumors, and most likely has no influence on the function of CEACAM1 in this tumor entity.

Detection of three common translocation breakpoints in non-Hodgkin's lymphomas by fluorescence in situ hybridization on routine paraffin-embedded tissue sections

Non-random chromosomal translocations are specifically involved in the pathogenesis of many non-Hodgkin's lymphomas and have clinical implications as diagnostic and/or prognostic markers. Their detection is often impaired by technical problems, including the distribution of the breakpoints over large genomic areas. This study reports a fluorescence in situ hybridization (FISH) method which allows the detection of specific chromosomal breakpoints in tissue sections from routinely fixed, paraffin-embedded samples. Hybridization was performed after demasking the DNA. Previously validated locus-specific probes (cosmids, PACs) flanking the BCL1, BCL2 regions and similar new probes for the MYC breakpoint region were used. The cases studied were five mantle cell lymphomas (MCL) and five follicular lymphomas (FL), selected on the basis of a previously proved t(11;14) and t(14;18) and five randomly chosen Burkitt's lymphomas (BL), as well as 21 negative control samples. In all samples, hybridization signals of sufficient intensity were obtained. Three different algorithms were used to score the hybridization signals in tissue sections, two of them taking into account the nuclei and their signal distribution indicative of chromosomal break, and one only considering the colocalization or segregation of the signals. In control tissues, these algorithms resulted in cut-off levels of 9.1%, 1.3%, or 10.0%. In the 15 lymphoma samples the percentages of abnormal cells/signals ranged from 28% to 80%, 13% to 49%, and 40% to 70%, respectively. The results indicate that small locus-specific probes can be used in FISH for regular detection of translocation breakpoints on routine paraffin tissue sections.

Primary peripheral PNET/Ewing's sarcoma of the dura: a clinicopathologic entity distinct from central PNET

We describe two cases of peripheral primitive neuroectodermal tumor-Ewing's sarcoma (PNET-ES) arising intracranially in the leptomeninges. Both tumors exhibited a primitive undifferentiated round-cell morphology. Immunohistochemical stains revealed strong membrane expression of CD99 in both cases. A t(11;22)(q24;q12) could be demonstrated with reverse transcriptase-polymerase chain reaction in one case, whereas fluorescence in situ hybridization analysis performed in the second case showed a rearrangement of the EWS gene. The occurrence of PNET-ES at this site is very unusual. Immunophenotypical as well as genetic analysis play a key role in the diagnosis and the distinction from central PNET.

Use of interphase fluorescence in situ hybridization as a powerful diagnostic tool in cytology

Interphase fluorescence in situ hybridization (I-FISH) using labeled nucleic acid probes detects chromosomal and genetic aberrations at a cellular level. I-FISH is a relatively fast and sensitive technique for evaluating a large number of cells and revealing more specific information than other techniques. It has been proven to be an invaluable molecular test in cytologic analyses for the detection of subtle genetic alterations that correlate with disease progression. In this postgenomic era, with the draft of the human genome available and expansion of the knowledge of tumor-specific genetic changes, the application of I-FISH probes in cytologic analysis should be of great value in the early detection, risk assessment, and monitoring of therapy efficacy in cancer. Here, we outline the principle of the I-FISH procedure, present suggestions to efficiently analyze cytologic materials, provide examples of practical applications, and discuss new aspects of the technique.

Amplification of c-myc oncogene by chromogenic and fluorescence in situ hybridization in archival breast cancer tissue array samples

Fluorescence in situ hybridization (FISH) is currently considered to be the most specific and sensitive method for detection of oncogene amplifications in human tumor samples. However, FISH requires fluorescence microscopy, which is tedious and does not allow histopathologic evaluation of the cells and tissues examined. Here we compared FISH with the newly developed chromogenic in situ hybridization (CISH), which uses peroxidase enzyme for probe detection instead of fluorescent dyes. CISH was found to be highly concordant with FISH in a tissue array series of 177 archival breast cancer samples. This was true both when comparing CISH with single-color and two-color FISH, the latter including the chromosome 8 centromere probe as reference (the kappa coefficients were 0.67 and 0.76, respectively). Clinicopathologic correlations of c-myc amplification as detected by FISH and CISH were generally the same. By both methods, c-myc amplification was significantly associated with high histologic grade, negative progesterone receptor status, DNA aneuploidy, and high S-phase fraction. c-myc amplification was strongly associated with poor distant metastasis-free survival when amplification was detected by CISH (p = 0.0013), but this association was weaker when FISH was used (p = 0.16 for two-color FISH and p = 0.065 for single-color FISH). These data suggest that CISH is at least as sensitive and specific as FISH in the detection of oncogene amplification in human tumor samples. The possibility for concomitant tissue architecture evaluation using an ordinary transmitted light microscope may favor the use of CISH over FISH in oncogene amplification detection in large tumor series, and tissue arrays and, ultimately, in routine clinical diagnostics.

Chromogenic in situ hybridization analysis of HER-2/neu status in breast carcinoma: application in screening of patients for trastuzumab (Herceptin) therapy

Evaluation of HER-2/neu status is important in the management of patients with breast carcinoma, especially in determining the possible application of trastuzumab, a humanized anti-HER-2/neu monoclonal antibody. Chromogenic in situ hybridization (CISH) detection of the HER-2/neu oncogene is a newly developed in situ hybridization method that utilizes a robust and unique-sequence DNA probe labeled with digoxygenin, and sequential incubations with antidigoxygenin fluorescein, antifluorescein peroxidase, and diaminobenzidine. In this study, we examined 20 archival specimens of human breast carcinoma using CISH, and we correlated findings with immunohistochemical findings for HER-2/neu. HER-2/neu immunohistochemistry was carried out with HercepTest, a standardized immunohistochemical examination system for HER-2/neu overexpression in surgical pathology specimens. CISH analysis could be done in 18 out of 20 cases examined. Gene copy signals for HER-2/neu were recognized as intranuclear brown dots in both neoplastic and non-neoplastic cells. Seven carcinomas showed an increased number or size of signals and were interpreted as being positive for HER-2/neu amplification. Eight cases were positive with the HercepTest. Seven out of eight carcinoma cases found to overexpress immunoreactive HER-2/neu also demonstrated HER-2/neu gene amplification following CISH analysis. There was a significant correlation between immunohistochemical and CISH analyses (P < 0.001). We found that CISH was a specific, sensitive and easily applicable method for the detection of HER-2/neu gene amplification, which may be used together with immunohistochemical examination for the evaluation of patients with breast carcinoma.

Isochromosome 7q in adult Wilms' tumors: diagnostic and pathogenetic implications

Wilms' tumors affecting adults are rare and are thought to have a worse prognosis than similar stage tumors in the pediatric population. To understand these tumors better, the authors reviewed their multi-institutional experience in a series of nine lesions diagnosed as Wilms' tumors in adults. In addition to histologic and immunohistochemical examination, they performed cytogenetic analysis and fluorescence in situ hybridization. On review, four cases were reclassified: two "blastema only" as Ewing's sarcoma/primitive neuroectodermal tumor and the other two as clear cell sarcoma of soft parts and sarcoma not otherwise specified (NOS). Of the remaining five cases, three exhibited biphasic histology and two were triphasic. In this group, there were three women and two men, and patient age ranged from 17 to 37 years (median age, 26 years). Tumor size was large and ranged from 10 to 31 cm (median tumor size, 12.5 cm). Histologically, the tumors showed the typical features of Wilms' tumors with varying amounts of blastema (n = 5), epithelium (n = 5), and stroma (n = 2). No tumors contained anaplasia, and persistent renal blastema was not identified in the non-neoplastic kidney in any specimen. All tumors were positive for cytokeratins (CK7, n = 3; pankeratin, n = 5), and one tumor was weakly positive for CD99 (0-13). Molecular analysis including dual color fluorescence in situ hybridization (all tumors), and cytogenetic analysis (n = 2) disclosed the presence of isochromosome 7q in three of five tumors whereas all tumors were diploid with respect to chromosome 12. Follow-up data ranged from 6 to 133 months (median follow-up, 82 months) with progression in only one patient who had stage IV disease with lymph node and lung metastases at presentation. The authors conclude that adult Wilms' tumor has been overdiagnosed. Most "blastema-only" tumors in adults are not Wilms' tumors, and in an adult, biphasic morphology should be the minimum criteria for their diagnosis. Using strict diagnostic criteria, adult Wilms' tumors have a relatively favorable prognosis. The characteristic findings of isochromosome 7q, lack of trisomy or tetrasomy for chromosome 12, and absence of persistent renal blastema suggest that the pathogenesis of Wilms' tumors in adults may be different than in the pediatric population. These genetic features may be helpful in distinguishing adult Wilms' tumors from other primary renal tumors.

Chromogenic in situ hybridization: a practical alternative for fluorescence in situ hybridization to detect HER-2/neu oncogene amplification in archival breast cancer samples

Determination of HER-2/neu oncogene amplification has become necessary for selection of breast cancer patients for trastuzumab (Herceptin) therapy. Fluorescence in situ hybridization (FISH) is currently regarded as a gold standard method for detecting HER-2/neu amplification, but it is not very practical for routine histopathological laboratories. We evaluated a new modification of in situ hybridization, the chromogenic in situ hybridization (CISH), which enables detection of HER-2/neu gene copies with conventional peroxidase reaction. Archival formalin-fixed paraffin-embedded tumor tissue sections were pretreated (by heating in a microwave oven and using enzyme digestion) and hybridized with a digoxigenin-labeled DNA probe. The probe was detected with anti-digoxigenin fluorescein, anti-fluorescein peroxidase, and diaminobenzidine. Gene copies visualized by CISH could be easily distinguished with a x40 objective in hematoxylin-stained tissue sections. HER-2/neu amplification typically appeared as large peroxidase-positive intranuclear gene copy clusters. CISH and FISH (according to Vysis, made from frozen pulverized tumor samples) correlated well in a series of 157 breast cancers (kappa coefficient, 0.81). The few different classifications were mostly because of low-level amplifications by FISH that were negative by CISH and immunohistochemistry with monoclonal antibody CB-11. We conclude that CISH, using conventional bright-field microscopy in evaluation, is a useful alternative for determination of HER-2/neu amplification in paraffin-embedded tumor samples, especially for confirming the immunohistochemical staining results.

Molecular biology of Burkitt's lymphoma

The diagnostic category of Burkitt's lymphoma encompasses a closely related group of aggressive B-cell tumors that includes sporadic, endemic, and human immunodeficiency virus-associated subtypes. All subtypes are characterized by chromosomal rearrangements involving the c-myc proto-oncogene that lead to its inappropriate expression. This review focuses on the roles of c-myc dysregulation and Epstein-Barr virus infection in Burkitt's lymphoma. Although the normal function of c-Myc remains enigmatic, recent data indicate that it has a central role in several fundamental aspects of cellular biology, including proliferation, differentiation, metabolism, apoptosis, and telomere maintenance. We discuss new insights into the molecular mechanisms of these c-Myc activities and their potential relevance to the pathogenesis of Burkitt's lymphoma and speculate on the role of Epstein-Barr virus.

Fluorescence in situ hybridization: molecular probes for diagnosis of pediatric neoplastic diseases

Fluorescence in situ hybridization (FISH) has become an important tool for diagnosing neoplasia in children. With probes designed to identify specific chromosomes and chromosomal regions, FISH is commonly used to detect the specific chromosomal abnormalities associated with hematologic diseases and solid tumors. Variations of FISH currently being investigated, such as comparative genomic hybridization, multicolor FISH, and microchip arrays, will probably result in additional uses of FISH in both research and clinical cytogenetic laboratories. Although FISH has disadvantages when compared with conventional cytogenetics and molecular methods, FISH will continue to be important in analyzing chromosomal abnormalities of tumors in children.

Clear cell sarcoma of soft parts: report of a case primary in the kidney with cytogenetic confirmation

Clear cell sarcoma of soft parts (CCSSP), also known as malignant melanoma of soft parts, is an aggressive tumor that usually presents in soft tissue and very rarely in small bowel. We report a case arising in the kidney of a 20-year-old man which was difficult to distinguish from Wilms' tumor. The tumor metastasized to the liver and lungs, and the patient died of disseminated disease 5 years after his initial presentation. Both the primary and metastatic tumors were composed predominantly of spindle cells with occasional more epithelioid areas that were inconsistently arranged in nests. In both primary and metastatic sites, the tumor surrounded and entrapped normal epithelial elements, mimicking the biphasic appearance of Wilms' tumor. The tumor cells, however, were positive for S-100 protein and HMB45 and negative for keratin and CD99, and cytogenetic analysis revealed a clonal abnormality, translocation t(12;22)(q13;q12), characteristic of CCSSP. This result was verified by fluorescence in situ hybridization on paraffin-embedded tissue, which demonstrated EWS gene-region rearrangement. CCSSP joins a growing list of tumors that typically arise in soft tissue (PNET, solitary fibrous tumor, and infantile/congenital fibrosarcoma), but can also present in the kidney and may be confused with primary renal tumors. Awareness of this possibility and the use of ancillary studies. including immunohistochemistry, cytogenetic analysis, and fluorescence in situ hybridization, are important for accurate diagnosis.