Fluorescent in Situ Hybridization (FISH): "A type of IN SITU HYBRIDIZATION in which target sequences are stained with fluorescent dye so their location and size can be determined using fluorescence microscopy. This staining is sufficiently distinct that the hybridization signal can be seen both in metaphase spreads and in interphase nuclei." (Source: MeSH 2013)
Recent Publications: FISH
FISH Resources (2 links)
Recent Publications: FISH
Automated Bright-Field Dual-Color In Situ Hybridization for MDM2: Interobserver Reproducibility and Correlation With Fluorescence In Situ Hybridization in a Series of Soft Tissue Consults.
Arch Pathol Lab Med. 2016; 140(10):1111-5 [PubMed] Related Publications
OBJECTIVE: -To assess the interobserver reproducibility of a bright-field assay for MDM2 amplification (dual-color, dual-hapten in situ hybridization [DDISH]) among reviewers with varying degrees of experience with the assay and to assess the concordance of MDM2 DDISH with MDM2 fluorescence in situ hybridization (FISH).
DESIGN: -In total, 102 cases were assessed in parallel for MDM2 by FISH and DDISH. MDM2 amplification was defined as an MDM2 to chromosome 12 ratio of 2.0 or greater, whereas an MDM2 to chromosome 12 ratio of less than 2 was nonamplified. Fluorescence in situ hybridization was scored in the routine clinical laboratory and DDISH was evaluated by 3 different pathologists blinded to the final diagnosis and FISH results.
RESULTS: -Fluorescence in situ hybridization categorized 27 cases (26%) as MDM2 amplified and 75 cases (74%) as nonamplified; the consensus DDISH diagnosis was 98% concordant with FISH. Agreement between MDM2 DDISH by each reviewer and MDM2 FISH was highly concordant (99%, 98%, and 98%, respectively, for reviewers 1, 2 and 3). The κ agreement of the 3 reviewers scoring DDISH was excellent (κ = 0.949, 0.95, and 0.95, respectively, for reviewers 1, 2, and 3).
CONCLUSIONS: -This study highlights excellent concordance between DDISH and FISH in MDM2 copy number assessment. Moreover, excellent interobserver reproducibility of the DDISH assay was found among reviewers with varying levels of experience evaluating bright-field assays.
Multiplexed automated digital quantification of fusion transcripts: comparative study with fluorescent in-situ hybridization (FISH) technique in acute leukemia patients.
Diagn Pathol. 2016; 11(1):89 [PubMed] Free Access to Full Article Related Publications
METHODS: "nCounter® Leukemia fusion gene expression assay" by NanoString was employed to detect various fusion transcripts in a large set samples (n = 94) utilizing RNA from formalin fixed paraffin embedded (FFPE) diagnostic bone marrow biopsy specimens. This series included AL patients with various recurrent translocations (n = 49), normal karyotype (n = 19), or complex karyotype (n = 21), as well as normal bone marrow samples (n = 5). Fusion gene expression data were compared with results obtained by conventional karyotype and FISH technology to determine sensitivity/specificity, as well as positive /negative predictive values.
RESULTS: Junction probes for PML/RARA; RUNX1-RUNX1T1; BCR/ABL1 showed 100 % sensitivity/specificity. A high degree of correlation was noted for MLL/AF4 (85 sensitivity/100 specificity) and TCF3-PBX1 (75 % sensitivity/100 % specificity) probes. CBFB-MYH11 fusion probes showed moderate sensitivity (57 %) but high specificity (100 %). ETV6/RUNX1 displayed discordance between fusion transcript assay and FISH results as well as rare non-specific binding in AL samples with normal or complex cytogenetics.
CONCLUSIONS: Our study presents preliminary data with high correlation between fusion transcript detection by a throughput automated multiplexed platform, compared to conventional karyotype/FISH technique for detection of chromosomal translocations in AL patients. Our preliminary observations, mandates further vast validation studies to explore automated molecular platforms in diagnostic pathology.
Comparison of the types of candidate reference samples for quality control of human epidermal growth factor receptor 2 status detection.
Diagn Pathol. 2016; 11(1):85 [PubMed] Free Access to Full Article Related Publications
METHODS: We used three different types of samples: formalin-fixed and paraffin-embedded (FFPE) samples prepared from cell lines, agarose gel samples using cell lines, and xenograft tumor samples. One cell line for FFPE or xenografts did not overexpress HER2, while the others showed different levels of HER2 overexpression. We compared the morphology, HER2 gene amplification status, and HER2 protein expression status of these samples with those of clinical specimens.
RESULTS: We successfully produced three kinds of samples for quality control. Cells from the cell line-sample sections were dispersed while those from the agarose gel-sample sections and xenograft tumor sample sections (prepared from the both cell lines) were concentrated in one area. The FISH results for all three kinds of samples were as expected. The IHC results of the cell line samples and xenograft tumor samples were as expected, but the staining level of the agarose gel samples, using HER2-overexpressed cell lines was weak which might be regarded as a false negative result.
CONCLUSIONS: Xenograft tumor samples might be used as an additional option for quality control in FISH and IHC. However, it might not replace the clinical specimen quality controls directly.
Common Fluorescence In Situ Hybridization Applications in Cytology.
Arch Pathol Lab Med. 2016; 140(12):1323-1330 [PubMed] Related Publications
OBJECTIVE: - To review common applications of FISH in cytology.
DATA SOURCES: - The published literature was reviewed.
CONCLUSIONS: - Cytology is particularly well suited for all kinds of FISH applications, which is highlighted in respiratory tract cytology with an increasing demand for predictive FISH testing in lung cancer. Fluorescence in situ hybridization is the gold standard for detection of predictive anaplastic lymphoma kinase gene (ALK) rearrangements, and the same evaluation criteria as in histology apply to cytology. Several other gene rearrangements, including ROS proto-oncogene 1 receptor tyrosine kinase (ROS1), are becoming clinically important and share the same underlining cytogenetic mechanisms with ALK. MET amplification is one of the most common mechanisms of acquired resistance to epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors and can be targeted by crizotinib. As genomic aberrations are a hallmark of malignant cells, FISH is a valuable objective ancillary diagnostic tool. In urinary tract cytology, atypical urothelial cells equivocal for malignancy are a common diagnostic dilemma and multitarget FISH can help clarify such cells. Diagnosis of malignant mesothelioma remains one of the most challenging fields in effusion cytology, and ancillary FISH is useful in establishing the diagnosis. Fluorescence in situ hybridization is a morphology-based technique, and the prerequisite for reliable FISH results is a targeted evaluation of the cells in question (eg, cancer or atypical cells). Cytopathologists and cytotechnicians should therefore be involved in molecular testing in order to select the best material and to provide their morphologic expertise.
Role of Tetrasomy for the Diagnosis of Urothelial Carcinoma Using UroVysion Fluorescent In Situ Hybridization.
Arch Pathol Lab Med. 2016; 140(6):552-9 [PubMed] Related Publications
OBJECTIVES: -To evaluate tetrasomy for UC detection and explore the relation to the surgical diagnosis or patient history.
DESIGN: -The FISH was performed on 1532 urine samples from patients with cytology results and 4 or more years of follow-up. We created separate polysomy and tetrasomy categories and constructed receiver operating curves to determine appropriate thresholds using biopsy (n = 194) as the gold standard. Standard FISH and a novel assay integrating cytomorphology and FISH (Target-FISH) were compared. Matching tissue biopsies of urine samples with 10 or more tetrasomy cells were analyzed.
RESULTS: -No significant threshold was found for tetrasomy cells. Exclusion of tetrasomy from the polysomy category changed the threshold from 8.5 to 4.5 cells, increased specificity (59.2% to 78.9%), but reduced sensitivity (78.9% to 65.9%). In Target-FISH, the same approach yielded a specificity of 93.7% and sensitivity of 65.2%. Similarly, specificity improved significantly for low- and high-grade UC, but sensitivity decreased for low-grade UC. No evidence of UC was observed in 95% (52 of 55) of the patients referred for screening who had 10 or more tetrasomy cells by FISH. Matching biopsies for urines containing 10 or more tetrasomy cells showed few or no tetrasomy cells.
CONCLUSIONS: -Tetrasomy is a nonspecific finding frequently encountered in urine FISH and should be excluded from the polysomy classification. Target-FISH is an optimal approach, offering the ability to detect rare tetrasomy tumors.
Use of p16 FISH for differential diagnosis of mesothelioma in smear preparations.
Diagn Cytopathol. 2016; 44(9):774-80 [PubMed] Related Publications
Diagnostic use of fluorescence in situ hybridization in expert review in a phase 2 study of trabectedin monotherapy in patients with advanced, translocation-related sarcoma.
Diagn Pathol. 2016; 11:37 [PubMed] Free Access to Full Article Related Publications
METHODS: TRS patients (n = 76) were enrolled in the trial at 12 study sites after pathological diagnoses were made, including morphological examination with or without evidence of translocation by genetic testing. Following histological reviews of the representative specimens at the study sites, we performed immunohistochemistry using the appropriate antibodies and FISH for genetic confirmation of the tumor types in the expert review.
RESULTS: Among the 76 TRS cases, no split signal for SS18 probe was detected by FISH in three synovial sarcoma cases that were diagnosed at the study sites. Malignant peripheral nerve sheath tumor (MPNST) was diagnosed in two cases and sarcomatoid carcinoma in one. One of the cases was a small round cell variant of MPNST. After excluding these three cases, we assessed the other 73. There were no split signals detected in 7 of the 73 cases by FISH analysis, due to decalcification and hyperfixation procedures. Excluding these seven cases, FISH detected translocations in 95 % (63/66) of the study cases with a high sensitivity.
CONCLUSIONS: The diagnosis of TRS by FISH was highly sensitive and enabled genetic confirmation of the pathological diagnoses. We strongly recommend FISH as a confirmatory diagnostic test for TRS, which would enable the selection of patients with TRS in whom trabectedin is expected to be effective. This study was done in part that registered with Japan Pharmaceutical Information Center, number JapicCTI-121850.
Clinical significance of pancreatic circulating tumor cells using combined negative enrichment and immunostaining-fluorescence in situ hybridization.
J Exp Clin Cancer Res. 2016; 35:66 [PubMed] Free Access to Full Article Related Publications
METHODS: In the present study, we applied a newly-developed platform integrated subtraction enrichment and immunostaining-fluorescence in situ hybridization (SE-iFISH) to analyze clinical significance of pancreatic CTCs. Immunostaining of CK, CD45, DAPI and FISH with the centromere of chromosome 8 (CEP8) were utilized to identify CTCs. Cells with features of CK+/CD45-/DAPI+/CEP8 = 2, CK+/CD45-/DAPI+/CEP8 > 2, CK-/CD45-/DAPI+/CEP8 > 2 were defined as pancreatic CTCs. The Kaplan-Meier method and Cox proportional hazards model were used to analyze the relationship of CTC level and other clinicopathological factors with pancreatic cancer clinical outcomes.
RESULTS: CTC count in pancreatic cancer was higher than healthy individuals (median, 3 vs. 0 per 7.5 ml; P < 0.001). SE-iFISH platform yielded a sensitivity of 88% and specificity of 90% in pancreatic cancer at the cutoff value of 2 cells/7.5 ml. Pancreatic cancer patients with lower CTC count (<3/7.5 ml) had substantially better overall survival (OS) compared with these with higher CTC count (≥3/7.5 ml) (15.2 vs. 10.2 months, P = 0.023). Multivariate analysis indicated that higher CTC count was a strong indicator for worse OS (HR = 4.547, P = 0.016).
CONCLUSION: Our current data showed that CTCs could be detected in pancreatic cancer patients in various stages, whether localized, locally advanced and metastatic. Besides, CTCs have shown the potential implication in predicting prognosis of pancreatic cancer.
INTERLABORATORY CONCORDANCE IN HER-2 POSITIVE BREAST CANCER.
Acta Clin Croat. 2015; 54(4):479-85 [PubMed] Related Publications
Fluorescence In Situ Hybridization for Melanoma Diagnosis: A Review and a Reappraisal.
Am J Dermatopathol. 2016; 38(4):253-69 [PubMed] Related Publications
Reliability of immunocytochemistry and fluorescence in situ hybridization on fine-needle aspiration cytology samples of breast cancers: A comparative study.
Diagn Cytopathol. 2016; 44(6):466-71 [PubMed] Related Publications
PATIENTS AND METHODS: We examined 110 breast cancer patients' paired cytological and surgical resection specimens evaluated between 2005 and 2014. Comparison of ER and Her2 immunocytochemical (ICC) and immunohistochemical (IHC) staining and HER2 fluorescence in situ hybridization (FISH) was performed.
RESULTS: Significant difference (p < 0.001) and moderate correlation (κ = 0.446) were noted between results of 97 paired ICC an IHC reactions for ER expression. ICC for ER status had a sensitivity of 75%, specificity of 100%, positive predictive value (PPV) of 100%, and negative predictive value (NPV) of 38.2%. Significant difference (p = 0.012) and moderate correlation (κ = 0.541) were found between results of 77 paired ICC an IHC reactions for Her2 expression. The Her2 ICC had a sensitivity of 54%, specificity of 95.4%, PPV of 66.7%, and NPV of 92.6%. The results of FISH carried out on 23 paired samples of FNAB and surgical specimens indicated perfect correlation (κ = 1.000) and no significant difference (p = 1.000). FISH performed on FNAB has sensitivity, specificity, PPV, and NPV of 100%.
CONCLUSION: The correlation of ICC and IHC is moderate regarding ER and Her2 expression of the same tumor. FISH performed on FNAB samples is suitable to categorize primary and metastatic breast cancer in regard of HER2 gene amplification status and can be used as a predictive test in respect of therapies targeting HER2. Diagn. Cytopathol. 2016;44:466-471. © 2016 Wiley Periodicals, Inc.
Detection of chromosomal changes in chronic lymphocytic leukemia using classical cytogenetic methods and FISH: application of rich mitogen mixtures for lymphocyte cultures.
J Investig Med. 2016; 64(4):894-8 [PubMed] Related Publications
Implications of the Updated 2013 American Society of Clinical Oncology/College of American Pathologists Guideline Recommendations on Human Epidermal Growth Factor Receptor 2 Gene Testing Using Immunohistochemistry and Fluorescence In Situ Hybridization for Breast Cancer.
Arch Pathol Lab Med. 2016; 140(2):140-7 [PubMed] Related Publications
OBJECTIVE: To assess the impact of the revised ASCO/CAP recommendations on both IHC and FISH results by using the dual-color HER2/neu and centromeric FISH probes.
DESIGN: Retrospective analysis of 590 invasive carcinomas with concurrent IHC and dual-color HER2/neu and centromeric 17 (CEP17) FISH results, based on 2007 ASCO/CAP guidelines, was conducted from July 2011 to June 2013. With the revised guidelines, patients were recategorized and concordance rates between the 2 assays were recalculated.
RESULTS: Overall concordance rates for FISH and IHC decreased from 94.9% to 93.8% with reclassification. Negative FISH cases decreased from 79.1% to 69.3%. However, equivocal FISH cases were significantly increased from 0.7% to 9.5%, leading to more retesting. Both positive IHC and FISH cases were also noted to be increased, leading to more patients being eligible for trastuzumab treatment, especially those patients with concurrent HER2/neu and CEP17 polysomy. Approximately 1% of patients with initial FISH negative results were reclassified as having positive results when both the ratios and average copy number of HER2/neu were considered under the revised guidelines.
CONCLUSIONS: The revised 2013 ASCO/CAP guidelines can potentially lead to more patients being eligible for trastuzumab therapy but additional retesting is to be expected owing to an increased number of equivocal FISH cases.
Histological diversity and clinical characteristics of Ewing sarcoma family of tumors in children: A series from a tertiary care center in South India.
Indian J Cancer. 2015 Jul-Sep; 52(3):331-5 [PubMed] Related Publications
MATERIALS AND METHODS: This retrospective descriptive study includes 51 cases of ES in children aged below 15 years. Clinical details were collected from case files. Histomorphological features were reviewed and tumors were subtyped into classic, primitive neuroectodermal tumor (PNET) and atypical variants along with immunohistochemical markers, cytogenetics, and fluorescence in situ hybridization (FISH).
RESULTS: Fifty-three percent were female and 47% were male with mean age of 10 years. The most common site of involvement was skeletal involvement in 71%, followed by soft tissue involvement in 23%, and visceral involvement in 6%. Localized disease at presentation was seen in 44%, locally advanced disease in 28%, and metastatic disease in 28%. Recurrence was documented during follow-up in 18% of the cases. Histomorphologically, classic type was the most common (72%) followed by PNET (20%) category and atypical variant (8%). All cases were immunoreactive for CD99. Cytogenetic study in 12 cases showed translocation t(11;22) (q24;12) in 80% and variant translocations such as t(3;16), t(3;11) with nonspecific numerical abnormalities in 20%. FISH was carried out for documentation of four cases with atypical histomorphology.
CONCLUSION: ESFT had wide histological variation which required confirmation by ancillary studies.
BAP1 Immunohistochemistry and p16 FISH in the Diagnosis of Sarcomatous and Desmoplastic Mesotheliomas.
Am J Surg Pathol. 2016; 40(5):714-8 [PubMed] Related Publications
HER2 FISH classification of equivocal HER2 IHC breast cancers with use of the 2013 ASCO/CAP practice guideline.
Breast Cancer Res Treat. 2016; 155(3):457-62 [PubMed] Related Publications
Diagnosis of adults Xp11.2 translocation renal cell carcinoma by immunohistochemistry and FISH assays: clinicopathological data from ethnic Chinese population.
Sci Rep. 2016; 6:21677 [PubMed] Free Access to Full Article Related Publications
In prostate cancer needle biopsies, detections of PTEN loss by fluorescence in situ hybridization (FISH) and by immunohistochemistry (IHC) are concordant and show consistent association with upgrading.
Virchows Arch. 2016; 468(5):607-17 [PubMed] Related Publications
The Dohner fluorescence in situ hybridization prognostic classification of chronic lymphocytic leukaemia (CLL): the CLL Research Consortium experience.
Br J Haematol. 2016; 173(1):105-13 [PubMed] Free Access to Full Article Related Publications
Should IGHV status and FISH testing be performed in all CLL patients at diagnosis? A systematic review and meta-analysis.
Blood. 2016; 127(14):1752-60 [PubMed] Related Publications
Comparison of fluorescence in-situ hybridisation with dual-colour in-situ hybridisation for assessment of HER2 gene amplification of breast cancer in Hong Kong.
Hong Kong Med J. 2016; 22(2):144-51 [PubMed] Related Publications
METHODS: This case series involved consecutive patients diagnosed with invasive breast carcinoma with equivocal immunohistochemistry score and referred for further HER2 assessment from the departments of Surgery and/or Clinical Oncology of the two hospitals between January 2013 and February 2014. An additional 10 cases with negative HER2 immunohistochemistry and 11 cases with positive HER2 immunohistochemistry were further included.
RESULTS: The results of both fluorescence in-situ hybridisation and dual in-situ hybridisation were available in 99 of 104 cases, respectively. Student’st test showed no statistically significant difference in the mean number of HER2 count, CEP17 copies, or HER2/CEP17 ratio between that obtained by fluorescence in-situ hybridisation and that obtained by dual in-situ hybridisation. Pearson’s correlation of results for the two assays was strong for HER2/CEP17 signal ratio (R=0.963, P<0.001) and mean HER2 copies per nucleus (R=0.897, P<0.001). Overall agreement was 96.0% (95 out of 99 cases, ĸ0.882). Three of the four discordant cases were equivocal for either fluorescence in-situ hybridisation or dual in-situ hybridisation. The results of immunohistochemistry 0/1+ and 3+ cases showed 100% concordance between the two assays. The failure rate was 0.96% for fluorescence in-situ hybridisation and 3.85% for dual in-situ hybridisation. Cases that failed for fluorescence in-situ hybridisation were successful for dual in-situ hybridisation and vice versa.
CONCLUSIONS: Our study showed that dual in-situ hybridisation is a reliable and useful option for HER2 testing in breast cancer.
Molecular cytogenetic analysis of dicentric chromosomes in acute myeloid leukemia.
Leuk Res. 2016; 43:51-7 [PubMed] Related Publications
Evaluation of Human Epidermal Growth Factor Receptor 2 (HER2) Gene Status in Human Breast Cancer Formalin-Fixed Paraffin-Embedded (FFPE) Tissue Specimens by Fluorescence In Situ Hybridization (FISH).
Methods Mol Biol. 2016; 1406:61-70 [PubMed] Related Publications
In Situ Hybridization of Breast Cancer Markers.
Methods Mol Biol. 2016; 1406:53-9 [PubMed] Related Publications
Doing more with less: fluorescence in situ hybridization and gene sequencing assays can be reliably performed on archival stained tumor tissue sections.
Virchows Arch. 2016; 468(4):451-61 [PubMed] Related Publications
A Comparison of IHC and FISH Cytogenetic Methods in the Evaluation of HER2 Status in Breast Cancer.
Adv Clin Exp Med. 2015 Sep-Oct; 24(5):899-903 [PubMed] Related Publications
Cervical FISH Testing for Triage and Support of Challenging Diagnoses: A Case Study of 2 Patients.
Lab Med. 2016; 47(1):52-6 [PubMed] Related Publications
Rapid diagnosis of acute promyelocytic leukemia with the PML-RARA fusion gene using a combination of droplet-reverse transcription-polymerase chain reaction and instant-quality fluorescence in situ hybridization.
Clin Chim Acta. 2016; 453:38-41 [PubMed] Related Publications
METHODS: RNA for droplet-RT-PCR and fixed-cell suspensions for IQ-FISH were prepared from five patients with APL and three controls. We evaluated the amplification efficiency and reaction time with droplet-RT-PCR and signal clarity and hybridization time with IQ-FISH.
RESULTS: The reaction using droplet-RT-PCR was completed in 26min. The PML-RARA fusion gene was detected in all samples from the five patients. IQ-FISH yielded clear signals after 1h of hybridization. There were no significant differences in signal clarity or positive signal ratios between IQ-FISH and conventional FISH.
CONCLUSIONS: Simultaneous droplet-RT-PCR and IQ-FISH, in addition to morphological examination of blood smears, can be used to diagnose patients as having APL within 4h based on molecular/cytogenetic results. Rapid diagnosis can allow effective therapies to be started promptly.
Chromogenic In Situ Hybridisation Test for Breast Cancer Patients with Equivocal IHC Results--a Study from Iran.
Asian Pac J Cancer Prev. 2015; 16(17):7695-700 [PubMed] Related Publications
MATERIALS AND METHODS: This study was conducted from 2008- 2010 using 334 consecutive breast carcinoma samples referred from local laboratories to Mehr Hospital. CISH assays were performed for all cases, and IHC tests were also done for determining efficacy and accuracy of local labs. HER2 status in local IHC tests was compared with central IHC and CISH results.
RESULTS: Of 334 breast cancer patients, 16 were negative for HER2 IHC (0, +1), 201 cases were equivocal (+2), and 31 positive (+3). Of 334 referral cases, 88 were CISH positive (26.3%) and 246 were CISH negative (73.7%). Of 201 IHC +2 cases, HER2 gene amplification was observed in 42 cases (kappa: 0.42). A 29.9% concordance was found between local IHC and central IHC. Sensitivity and specificity of local IHC were 90% and 53.8%, respectively.
CONCLUSIONS: Low accuracy of IHC results in local labs was associated with the following factors: using former FDA-approved criteria for HER2 interpretation, utilizing non-validated kits, and lack of any quality assurance program. Therefore, following the new 2014 ASCO/CAP guideline and comprehensive quality assurance should be implemented to ensure accuracy of HER2 testing.
Grb7 gene amplification and protein expression by FISH and IHC in ovarian cancer.
Int J Clin Exp Pathol. 2015; 8(9):11296-304 [PubMed] Free Access to Full Article Related Publications
METHODS: We use Tissue Microarray (TMA) respectively to detect the gene amplification and protein expression of Grb7 in 90 cases OC and 10 control specimens of normal ovarian tissues by IHC and FISH.
RESULTS: The Grb7 protein expression by IHC analysis was observed in 52/90 (57.8%) OC with 3 cases (3.3%) scored 3(+) and 9 cases (10%) scored 2(+) Grb7 gene amplification by FISH analysis was successfully detectable in 6 specimens with a positive rate of 6.8% (6/88) in which immunostaining 3(+), 2(+) and negative (1(+)/0) expressions of Grb7 were 100.0% (3/3), 11.1% (1/9) and 2.6% (2/76), respectively. Our data exhibited that the IHC and FISH results had a good consistency between Grb7 gene amplification and Grb7 protein expression (Kappa = 0.651, P < 0.001). Both the results of IHC and FISH revealed that Grb7 did not seem to have a role in OC clinicopathology.
CONCLUSION: There is a close relationship between Grb7 gene amplification and GRB7 protein overexpression in human OC. IHC might have limited diagnostic value especially in these tumors and especially in characterizing genetically diverse borderline cases, FISH could be superior to IHC.