BRAF V600E Immunohistochemistry Research Articles

Molecular Predictors for Advanced Papillary Thyroid Carcinoma Recurrence.

Despite its indolent course, one-third of the papillary thyroid carcinoma (PTC) cases relapses, which directly impact on the quality of patients' lives. The molecular predictors of recurrence of PTC are poorly defined. We aimed at evaluating the long-term (10–20 years) prognostic value of aggressiveness markers in advanced PTC. To this end, immunohistochemistry for BRAFV600E, Estrogen receptor α, Progesterone receptor, Ki-67, and E-cadherin were performed in 53 primary advanced PTC from an up to 20 years follow-up patients from a well-characterized Brazilian cohort. Categorical data were summarized using frequencies and groups were compared using Chi-squared and Fisher's exact tests. The expressions of the aggressiveness markers were associated with clinical-pathological data using the single-covariate logistic regression analysis. The Kaplan-Meier method with the Log-rank and Peto tests was used to estimate the probability of PTC-free survival. Persistence and recurrence (active disease) were associated with age (≥55 years), tumor size (>2 cm), extrathyroidal extension, local aggressiveness, macroscopic lymph node metastasis, and TNM stage at initial treatment. The BRAFV600E mutation status was associated with extrathyroidal extension, local aggressiveness, and inversely associated with distant metastasis at initial treatment. All progesterone receptor-positive patients had active disease and displayed a shorter time of PTC-free survival than the negative ones using the Kaplan-Meir analysis (p = 0.001, Log Rank; p = 0.005, Peto). Loss of E-cadherin expression was associated with an increase in the probability of active disease (OR = 3.75). BRAFV600E could be useful as a biomarker of local aggressiveness, while PR positive and E-cadherin loss of expression could predict the recurrence of advanced PTC.

Metanephric Adenoma-Epithelial Wilms Tumor Overlap Lesions: An Analysis of BRAF Status.

Metanephric adenoma (MA) has historically been considered to represent a differentiated form of epithelial Wilms tumor (WT), based in part upon cases that morphologically overlap these 2 neoplasms. More recently, BRAF V600E mutations have been demonstrated in the majority of MAs but not in unselected or even epithelial-predominant WTs, suggesting 2 genetically distinct entities. However, no prior study has examined BRAF status in neoplasms with overlapping histologic features of epithelial WT and MA. We studied a cohort of 11 such overlapping lesions, 2 of which we considered morphologically to be otherwise typical MAs with unusually prominent mitotic activity and 9 of which we classified as epithelial WTs with areas resembling MA. Both mitotically active MAs demonstrated the BRAF V600E mutation. While the majority (5/9) of epithelial WTs with areas resembling MA were negative for BRAF V600E mutation, 4 such cases were positive. Two BRAF V600E mutation-positive WTs occurred in children. One case in a 6-year-old male was morphologically similar to the BRAF V600E mutation-positive adult cases and subsequently metastasized to the lungs; remarkably, the metastases then completely resolved on Braf targeted therapy. A second occurred in a 3-year-old girl whose posttherapy nephrectomy specimen's tumor was encapsulated and mitotically active like a typical WT, but also had more differentiated areas resembling MA. Immunohistochemistry for Braf V600E paralleled the molecular findings, demonstrating immunoreactivity in both the WT and MA-like areas of all 4 of these neoplasms. In summary, we demonstrate that BRAF V600E mutations are not entirely restricted to typical MA, as they may be seen in MAs showing mitotic activity along with a subset of epithelial-predominant WTs in adults and children that have foci which overlap morphologically with MA.

Immunohistochemistry Critical Assay Performance Controls (ICAPC) Reduce Interobserver Variability in the Interpretation of BRAFV600E Immunohistochemistry

The utility of prognostic and predictive immunohistochemistry biomarkers in the context of cancer is plagued by inconsistent interpretation of results which can lead to poor rates of adoption or inappropriate use of novel therapeutic strategies. To monitor immunohistochemistry assay performance, a new on-slide control motif, Immunohistochemistry Critical Assay Performance Controls (ICAPC) was developed. We hypothesized that the use of these controls by the diagnosing pathologist to interpret BRAFV600E would result in reduced interobserver and intraobserver interpretation errors. A cross-sectional, sequentially obtained sample of surgical pathology cases stained for BRAFV600E was assembled from a single hospital in Vancouver, British Columbia. Half of the cases had normal on-slide controls and the remainder with ICAPC. Results from 6 independent and blinded readers were compared with each other and to the gold-standard pathologic diagnosis with the goal of demonstrating superior interrater agreement with ICAPC relative to standard on-slide controls. Cohen's κ was used to compute pair-wise reader agreements, whereas Fleiss' κ was used to compare to the gold standard. The implementation of ICAPC resulted in statistically significant improvements in the interobserver agreement of BRAF mutation status ascertained by BRAFV600E immunohistochemistry. Half of the readers demonstrated significant improvements in agreement with the gold-standard diagnosis with the addition of ICAPC. Across all readers, the mean increase in κ was 0.14 with a 95% confidence interval of 0.01-0.28 (P=0.04). This study demonstrates that the addition of ICAPC serves to significantly reduce interobserver variability in the assessment of BRAFV600E immunohistochemistry. As such, we recommend that this approach should be used as part of a comprehensive quality management strategy in the setting of histopathology.

Correlation between mismatch-repair protein expression and clinicopathologic features in 658 colorectal cancers

Objective: To investigate the expression of mismatch repair (MMR) proteins (MLH1, MSH2, MSH6 and PMS2) in colorectal cancers and to explore the relationship between MMR expression and clinicopathologic features. Methods: Six hundred and fifty-eight colon cancers were collected from January 2016 to January 2017 at Shengjing Hospital of China Medical University. Of the 658 patients there were 409 male and 249 female. The patients were 20 to 92 years old, with average age of (63±5) years old. Expression of MLH1, MSH2, MSH6 and PMS2 protein was detected by immunohistochemical method. Immunohistochemistry for BRAF V600E was performed in colorectal cancers with loss of MLH1 protein expression. Relationship between MMR protein expression and clinicopathologic features was analyzed statistically. Results: Forty-four cases of 658 cases (6.7%) lost at least one MMR protein expression. Expression deficiency rates of MLH1, MSH2, MSH6 and PMS2 were 4.1%(27/658), 2.3%(15/658), 2.4% (16/658), and 4.3% (28/658), respectively. MMR expression deficiency mainly consisted of combined loss of MLH1/PMS2 (61.4%, 27/44) and MSH2/MSH6 (34.1%, 15/44). Two unique mutations were identified including one MSH6-deficient(2.3%, 1/44) and PMS2-deficient(2.3%, 1/44). Seven cases (25.9%, 7/27) had positive BRAF V600E expression, suggesting BRAF gene mutation related sporadic colorectal cancers. No correlation was observed between the expression of MMR and depth of tumor infiltration, lymph node metastasis, vascular tumor emboli, clinical stage or hematogenous metastasis (P>0.05). MMR status was associated with tumor cell differentiation, histological type and tumor location (P<0.01). Tumors with combined MLH1 and PMS2 loss were associated with mucinous differentiation (P=0.049, P=0.013) and located in the right hemi-colon (P=0.006, P=0.002). Combined MSH2 and PMS2 loss was related to gender, while loss of MSH2 protein was observed more frequently in female patients (P=0.048) and loss of PMS2 protein was seen more frequently in male patients (P=0.031). Conclusions: Patients with MMR protein deficiency have a younger onset age and poorly differentiated tumors. Most tumors are located in the right hemi-colon and have mucinous differentiation.

Clinical utility of immunohistochemistry using the novel anti-BRAF V600E antibody (clone RM8) for detection of the BRAF V600E mutant protein in papillary thyroid cancers

&lt;p&gt;&lt;strong&gt;Background:&lt;/strong&gt;&lt;strong&gt; &lt;/strong&gt;Molecular markers are gaining increasing importance as diagnostic and prognostic tools in patients with well differentiated thyroid cancers and BRAF V600E mutation has received wide attention in this regard &lt;strong&gt;Aim: &lt;/strong&gt;To evaluate the clinical value of immunohistochemistry (IHC) using anti-BRAF V600E antibody (clone RM8) for detection of the BRAF V600E mutant protein in formalin-fixed and paraffin-embedded tissues of patients with papillary thyroid carcinomas. &lt;strong&gt;Materials and Methods: &lt;/strong&gt;Patients who were managed for well differentiated thyroid cancers (&lt;em&gt;n &lt;/em&gt;= 79) during the years 2005 and 2006 were included in the study. We evaluated the fidelity of the RM8 antibody specific for the BRAF V600E and compared its detection accuracy to real time polymerase chain reaction (PCR), which was taken as the gold standard. &lt;strong&gt;Results: &lt;/strong&gt;Mutant BRAF V600E antibody was studied in 79 tissue sections, out of which 21 (26.5%) had staining for BRAF V600E in &amp;gt;20% of the tumour cells and these were considered positive. The BRAF staining was moderate in 10 (47.6%), strong in 9 (42.5%) and very strong in 2 (9.5%) of sections stained. There was a statistically significant concordance (&lt;em&gt;P &lt;/em&gt;= 0.000) with quantitative PCR (qPCR) for BRAF mutant taken as standard. (Kappa agreement: 0.881) Further, the receiver operating characteristics (ROC) curve showed that IHC can be used as a comparable standard to the qPCR. The highest possible sensitivity of 92% and specificity of 92.6% could be achieved by considering the cytoplasmic positivity of &amp;gt;20% of cells with moderate to strong intensity (AUC = 0.923) &lt;strong&gt;Conclusion: &lt;/strong&gt;Our study has shown that BRAF V600E IHC can be done in a conventional manner using rabbit monoclonal antibody RM8 on formalin-fixed and paraffin-embedded tissues of patients with papillary thyroid carcinomas. With a comparable diagnostic accuracy to the gold standard qPCR testing and with an added advantage of being cost effective, this technology can be considered for use as a first-line method for detection of BRAF V600E mutations, especially in resource constrained settings.&lt;/p&gt;

Metastatic thyroid carcinoma without identifiable primary tumor within the thyroid gland: a retrospective study of a rare phenomenon

Metastatic papillary thyroid carcinoma (PTC) without an identifiable primary tumor despite extensive microscopic examination of the thyroid gland is a rare but true phenomenon.We retrieved 7 of such cases and described in detail the clinical and pathologic features of these tumors. BRAF V600E immunohistochemistry and Sequenom molecular profile were conducted in selected cases. All patients harbored metastatic disease in the central (n=3), lateral (n=3), or both neck compartments (n=1). The histotype of the metastatic disease was PTC (n=5), poorly differentiated thyroid carcinoma in association with a PTC columnar variant (n=1), and anaplastic thyroid carcinoma in association with a PTC tall cell variant (n=1). Fibrosis was present in the thyroid of 5 patients. All patients with PTC were alive without evidence of recurrence. The 76-year-old patient with poorly differentiated thyroid carcinoma did not recur and died of unknown causes. Finally, the patient with anaplastic thyroid carcinoma was alive with distant metastasis at last follow-up. The median follow-up for this cohort was 2.2years (range, 0.8-17). BRAF V600E was detected in 4 of 6 cases by immunohistochemistry. In conclusion, metastatic nodal disease without identifiable thyroid primary is a rare but real phenomenon of unknown mechanisms. Although most tumors are low grade and well differentiated, aggressive behavior due to poorly differentiated or anaplastic carcinoma can happen. Most cases are BRAFV600E-positive thyroid tumors. A papillary carcinoma phenotype is found in all reported cases.

The use of BRAF V600E mutation-specific immunohistochemistry in pediatric Langerhans cell histiocytosis.

BRAF p.V600E mutations are detected in greater than 50% of pediatric Langerhans cell histiocytosis (LCH) lesions. However, the use of mutation-specific BRAF V600E immunohistochemistry (IHC) as a surrogate for molecular testing in pediatric LCH is unknown. We tested the mutation-specific BRAF V600E monoclonal antibody (clone VE1) in formalin-fixed, paraffin-embedded LCH samples from 26 pediatric patients (14 males and 12 females, ages 7mo-17y) using allele-specific real-time polymerase chain reaction (PCR) with a limit of detection of 0.5% as the comparative gold standard. BRAF VE1 staining was scored for both intensity (0-3+) and percentage of immunoreactive tumor cells (0%-100%). BRAF VE1 immunoreactivity was determined using both lenient (≥1+, ≥1%) and stringent (≥2+, ≥10%) scoring criteria. Using lenient-scoring criteria, we found that the sensitivity and specificity of IHC compared with allele-specific real-time PCR were 100.0% and 18.2%, respectively. The poor specificity of lenient IHC analysis was attributable to weak, 1+ staining in both BRAF-mutated and wild-type LCH. Using stringent-scoring criteria, we found that specificity improved to 100.0% at the expense of sensitivity that decreased to 80.0%. Stringent scoring generated 3 false-negative results, but in all cases, neoplastic tissue comprised less than 5% of the stained section and/or the specimen was decalcified. In conclusion, highly sensitive molecular assays remain the gold standard for BRAF mutation analysis in LCH paraffin-embedded lesions. To avoid false-positive results, unequivocal VE1 staining of 2+ intensity in greater than or equal to 10% neoplastic histiocytes is required. However, negative VE1 results require additional studies to exclude false-negatives, and stringent-scoring criteria may not be optimal for scant or decalcified specimens.

Molecular features of metanephric adenoma and their values in differential diagnosis

Objective: To study the molecular features of metanephric adenoma (MA) and discuss their values in differential diagnosis. Methods: BRAF V600E immunohistochemistry (IHC) using the mutation-specific VE1 monoclonal antibody and Sanger sequencing of BRAF mutations were performed on 21 MAs, 16 epithelial-predominant Wilms tumors (e-WT) and 20 the solid variant of papillary renal cell carcinomas (s-PRCC) respectively. p16 protein was detected by IHC also. Fluorescence in situ hybridization (FISH) analyses using centromeric probes for chromosome 7 and 17 were performed on the three renal tumors in parallel. Results: Fourteen (14/21, 66.7%) of 21 MA cases demonstrated diffuse, moderate to strong cytoplasmic BRAF V600E IHC staining and the BRAF V600E protein expression was detected in 2 (2/16) of 16 e-WT cases for the first time, whereas all s-PRCCs were negative (P<0.05). All cases (including 14 MAs and 2 e-WTs) with diffuse, moderate to strong cytoplasmic BRAF V600E IHC staining were confirmed to harbor BRAF V600E missense mutations using Sanger sequencing, and no BRAF mutations were detected in cases with negative BRAF V600E protein expression. One case (1/21, 4.8%) showed trisomy of chromosome 7 alone, and another one (1/21, 4.8%) showed trisomy of chromosome 17 alone in 21 MAs. Two cases (2/16) of 16 e-WTs showed trisomy of chromosome 17 alone. In 20 s-PRCCs, trisomy of chromosomes 7 alone was reported in 2 cases (2/20), trisomy of chromosome 17 alone in 3 cases (3/20) and trisomy of chromosome 7 and 17 in 14 cases (14/20). The total positive rates of trisomy of chromosome 7 and/or 17 in MAs, e-WTs and s-PRCCs were 9.6% (2/21), 2/16 and 95.0% (19/20). p16 protein was positive in 81.0% (17/21) MAs, whereas the positive rates in e-WTs and s-PRCCs were 2/16 and 5.0% (1/20). Conclusions: Most MAs harbor BRAF V600E mutations, and MAs lack the gains of chromosome 7 and 17 that are characteristic of papillary renal cell carcinoma. These molecular features can be used to distinguish MA from its mimics. BRAF V600E IHC using the mutation-specific VE1 monoclonal antibody provides an effective method in BRAF V600E mutations detection of renal tumors. p16 is overexpressed in MA, and the finding suggests that the low proliferative rate of the tumor might be attributed to BRAF V600E-induced senescence mediated by p16.

Immunohistochemical staining for p16 and BRAFV600E is useful to distinguish between sporadic and hereditary (Lynch syndrome-related) microsatellite instable colorectal carcinomas.

DNA mismatch repair (MMR) protein analysis by immunohistochemistry (IHC) can identify colorectal cancer (CRC) with microsatellite instability (MSI). As MLH1-deficient CRC can be hereditary or sporadic, markers to distinguish between them are needed. MLH1 promoter methylation assay is the reference method; however, sometimes, it is challenging on formalin-fixed paraffin-embedded tissue samples. We assessed by IHC the expression of BRAFV600E, p16, MGMT, and CDX2 in 55 MLH1-deficient MSI CRC samples (of which 8 had a germline MLH1 mutation) to determine whether this panel differentiates between sporadic and hereditary CRCs. We also analyzed MLH1 promoter methylation by methylation-specific PCR and pyrosequencing and BRAF status by genotyping. None of the hereditary CRCs showed MLH1 methylation, BRAF mutation, BRAFV600E-positive immunostaining, or loss of p16 expression. We detected MLH1 promoter methylation in 67% and a BRAF mutation in 42% of CRC, all showing MLH1 promoter methylation. BRAFV600E IHC and BRAF genotyping gave concordant results in all but two samples. Loss of expression of p16 was found in 30% of CRC with methylation of the MLH1 promoter, but its expression was retained in all non-methylated and part of MLH1-methylated tumors (100% specificity, 30% sensitivity). CDX2 and MGMT expression was not associated with MLH1 status. Thus, BRAFV600E and p16 IHC may help in differentiating sporadic from hereditary MLH1-deficient CRC with MSI. Specifically, p16 IHC might be used as a surrogate marker for MLH1 promoter methylation, because all p16-negative CRCs displayed MLH1 methylation, whereas hereditary CRCs were all p16-positive.

Albumin expression distinguishes bile duct adenomas from metastatic adenocarcinoma.

Bile duct adenomas may be difficult to distinguish from metastatic carcinomas, particularly well-differentiated pancreatic ductal adenocarcinoma. Prior studies have evaluated the utility of various immunohistochemical markers, although these markers are notable for low sensitivity and/or specificity. The aim of this study was to investigate the utility of albumin and BRAFV600E expression in distinguishing between metastatic pancreatic adenocarcinoma and bile duct adenoma. We studied 26 bile duct adenomas, three bile duct hamartomas, and 158 pancreatic ductal adenocarcinomas. Branched-chain in-situ hybridization (bISH) for albumin was performed; bISH is based on the branched DNA technology, wherein signal amplification is achieved via a series of sequential steps. Additionally, BRAFV600E immunohistochemistry (IHC) was performed on a subset of cases. Twenty-three of 25 (92%) bile duct adenomas were positive for albumin; 18 (72%) showed diffuse staining, and five showed focal staining (20%), including two challenging examples. Two bile duct hamartomas also stained positively. All pancreatic adenocarcinomas were negative for albumin. Seven of 16 (44%) bile duct adenomas and five of 106 (5%) pancreatic ductal adenocarcinomas were positive for BRAFV600E by IHC. The sensitivity and specificity ofexpression of albumin, as detected by bISH, for distinguishing bile duct adenomas from metastatic pancreatic adenocarcinomas were 92% and 100%, respectively; the sensitivity and specificity of BRAFV600E IHC for distinguishing bile duct adenomas from metastatic pancreatic adenocarcinomas were 43.8% and 95.3%, respectively. Diagnostically challenging examples of bile duct adenoma may be distinguished from metastatic pancreatic adenocarcinoma by the use of albumin bISH.

High specificity and sensitivity of NRAS Q61R immunohistochemistry (IHC) in melanomas

High specificity and sensitivity of NRAS Q61R immunohistochemistry (IHC) in melanomas

Specific immunohistochemical detection of the BRAF V600E mutation in primary and metastatic papillary thyroid carcinoma

PurposeTo evaluate the clinical value of immunohistochemistry (IHC) using anti-BRAF V600E antibody (clone VE1) for specific detection of the BRAF V600E mutant protein in formalin-fixed paraffin-embedded papillary thyroid carcinoma (PTC) specimens. MethodsA total of 118 PTC cases and 116 control cases processed between January 2008 and June 2010 were selected and created tissue microarrays (TMAs) for the study. BRAF V600E (VE1) IHC was performed on tissue sections from PTC cases to determine mutation status. Molecular tests (Sanger sequencing/ARMS) were used to confirm the BRAF V600E gene mutation in primary PTC. ResultsA uniformly cytoplasmic staining throughout the tumors was observed in IHC-positive cases. BRAF V600E was detected in 68.6% (81/118) of PTC samples by IHC and in 61.9% (73/118) by Sanger sequencing/ARMS. The overall concordance between IHC and Sanger sequencing/ARMS was 93.2% (110/118). The sensitivity and specificity of the BRAF V600E IHC was 100% (73/73) and 82.2% (37/45), respectively. Positive and negative predictive values were 90.1% (73/81) and 100% (37/37), respectively. Expression of the BRAF V600E mutant protein was detected in all of 59 cases of primary carcinoma and corresponding metastatic carcinoma in lymph nodes. The concordance between IHC staining in primary and metastatic PTC was 100% (59/59). ConclusionIHC using VE1 antibody for detection of the BRAF V600E mutant protein expression in PTC showed high sensitivity and acceptable specificity, which are critical for diagnostic purposes. IHC staining for BRAF V600E showed uniformly cytoplasmic expression in both primary tumor and metastatic nodes. Therefore, IHC has high practical value for the detection of the BRAF V600E mutation in metastatic and primary PTC.

A combination of immunohistochemistry and molecular approaches improves highly sensitive detection of BRAF mutations in papillary thyroid cancer.

The optimal method for BRAF mutation detection remains to be determined despite advances in molecular detection techniques. The aim of this study was to compare, against classical Sanger sequencing, the diagnostic performance of two of the most recently developed, highly sensitive methods: BRAF V600E immunohistochemistry (IHC) and peptide nucleic-acid (PNA)-clamp qPCR. BRAF exon 15 mutations were searched in formalin-fixed paraffin-embedded tissues from 86 papillary thyroid carcinoma using the three methods. The limits of detection of Sanger sequencing in borderline or discordant cases were quantified by next generation sequencing. BRAF mutations were found in 74.4% of cases by PNA, in 71% of cases by IHC, and in 64% of cases by Sanger sequencing. Complete concordance for the three methods was observed in 80% of samples. Better concordance was observed with the combination of two methods, particularly PNA and IHC (59/64) (92%), while the combination of PNA and Sanger was concordant in 55 cases (86%). Sensitivity of the three methods was 99% for PNA, 94.2% for IHC, and 89.5% for Sanger. Our data show that IHC could be used as a cost-effective, first-line method for BRAF V600E detection in daily practice, followed by PNA analysis in negative or uninterpretable cases, as the most efficient method. PNA-clamp quantitative PCR is highly sensitive and complementary to IHC as it also recognizes other mutations besides V600E and it is suitable for diagnostic purposes.

Utility of BRAF V600E Immunohistochemistry Expression Pattern as a Surrogate of BRAF Mutation Status in 154 Patients with Advanced Melanoma.

Successful BRAF inhibitor therapy depends on the accurate assessment of the mutation status of the BRAF V600 residue in tissue samples. In melanoma, immunohistochemical (IHC) analysis with monoclonal anti-BRAF V600E has emerged as a sensitive and specific surrogate of BRAF V600E mutation, particularly when BRAF V600E protein expression is homogeneous and strong. A subset of melanomas exhibit heterogeneous labeling for BRAF V600E, but our understanding of the significance of heterogeneous BRAF V600E IHC expression is limited. We used next-generation sequencing to compare BRAF V600E IHC staining patterns in 154 melanomas: 79 BRAF(WT) and 75 BRAF (including 53 V600E) mutants. Agreement among dermatopathologists on tumor morphology, IHC expression, and intensity was excellent (ρ = 0.99). A predominantly epithelioid cell phenotype significantly correlated with the BRAF V600E mutation (P = .0085). Tumors demonstrating either heterogeneous or homogeneous IHC expression were significantly associated with the BRAF V600E mutation (P < .0001), as was increased intensity of staining (P < .0001). The positive predictive value was 98% for homogenous IHC expression compared with 70% for heterogeneous labeling. Inclusion of both heterogeneous and homogeneous BRAF V600E IHC expression as a positive test significantly improved IHC test sensitivity from 85% to 98%. However, this reduced BRAF V600E IHC test specificity from 99% to 96%. Cautious evaluation of heterogeneous BRAF V600E IHC expression is warranted and comparison with sequencing results is critical, given its reduced test specificity and positive predictive value for detecting the BRAF V600E mutation.

Molecular and immunohistochemical characterization reveals novel BRAF mutations in metanephric adenoma.

Metanephric adenoma (MA) is a rare benign renal tumor comprised of a neoplastic proliferation of primitive metanephric tubular cells. A previous study identified BRAF V600E mutations in approximately 90% of MA and found that similar BRAF exon 15 mutations are exceedingly rare in other common renal tumors, including renal cell carcinoma and oncocytoma. A recent follow-up study has validated mutation-specific immunohistochemistry (IHC) for detection of BRAF V600E mutations in a small cohort of MA. Here, we extend these findings to a larger, independent cohort of MA, demonstrating an overall 88% sensitivity and 100% specificity for BRAF V600E IHC. In addition, we report 2 cases of MA with novel BRAF exon 15 mutations, including a V600D missense mutation and a compound V600D and K601L missense mutation. Finally, we evaluate BRAF V600E IHC in a large tissue microarray cohort of common renal tumors and find no significant expression in several renal cell carcinoma subtypes. These data support a role for BRAF V600E IHC in diagnostically challenging cases of MA and expand the spectrum of BRAF exon 15 mutations in this uncommon but unique renal neoplasm.

BRAF VE1 immunoreactivity patterns in epithelioid glioblastomas positive for BRAF V600E mutation.

Epithelioid glioblastomas (E-GBMs) manifest BRAF V600E mutation in up to 50% of cases, compared with a small percentage of ordinary GBMs, suggesting that they are best considered variants rather than a different pattern of GBM. Availability of a targeted therapy, vemurafenib, may make testing BRAF status important for treatment. It is unclear whether BRAF VE1 immunohistochemistry (IHC) can substitute for Sanger sequencing in these tumors. BRAF VE1 IHC was correlated with Sanger sequencing results on our original cohort of E-GBMs, and then new E-GBM cases were tested with both techniques (n=20). Results were compared with those in similarly assessed giant cell GBMs, anaplastic pleomorphic xanthoastrocytomas. All tumors tested showed 1:1 correlation between BRAF V600E mutational results and IHC. However, heavy background immunostaining in some negatively mutated cases resulted in equivocal results that required repeat IHC testing and additional mutation testing using a different methodology to confirm lack of detectable BRAF mutation. Mutated/BRAF VE1 IHC E-GBMs and anaplastic pleomorphic xanthoastrocytomas tended to manifest strong, diffuse cytoplasmic immunoreactivity, compared with previously studied gangliogliomas, which demonstrate more intense immunoreactivity in the ganglion than in the glial tumor component. One of our E-GBM patients with initial gross total resection quickly recurred within 4 months, required a second resection, and then was placed on vemurafenib; she remains tumor free 21 months after second resection without neuroimaging evidence of residual disease, adding to the growing number of reports of successful treatment of BRAF-mutated glial tumors with drug. E-GBMs show good correlation between mutational status and IHC, albeit with limitations to IHC. E-GBMs can respond to targeted therapy.

An immunohistochemical study of potential diagnostic and therapeutic biomarkers of wild-type gastrointestinal stromal tumours.

The aims of this study were to investigate whether succinate dehydrogenase B (SDHB), insulin growth factor 1 receptor (IGF1R), HER2, epidermal growth factor receptor (EGFR) and/or BRAF V600E immunohistochemistry could screen for wild-type gastrointestinal stromal tumours (GISTs), and to determine what proportion of wild-type GISTs expressed these proteins and might therefore represent candidates for targeted therapies. Twenty-seven wild-type GISTs and 91 KIT-mutated or PDGFRA-mutated GISTs were immunostained for SDHB, IGF1R, HER2, and EGFR. A preliminary study of the BRAF VE1 antibody showed non-specific staining, and indicated it was neither a specific nor a sensitive marker of wild-type GISTs. SDHB loss showed 100% specificity but only 37% sensitivity as such a marker. EGFR and IGF1R were expressed by 63% and 33% of the wild-type GISTs but also by 56% and 32% of the KIT/PDGFRA mutant GISTs, respectively. Therefore, adding EGFR and/or IGF1R to SDHB as a panel only decreased the specificity of SDHB loss as a marker for wild-type status. All five antibodies failed, individually or collectively, to represent highly sensitive and highly specific markers for wild-type GIST. However, whereas HER2 has been excluded as a therapeutic biomarker, both EGFR and IGF1R are expressed by some wild-type GISTs and are therefore potential therapeutic targets.

A modified Lynch syndrome screening algorithm in colon cancer: BRAF immunohistochemistry is efficacious and cost beneficial.

Somatic BRAF mutation in colon cancer essentially excludes Lynch syndrome. We compared BRAF V600E immunohistochemistry (IHC) with BRAF mutation in core, biopsy, and whole-section slides to determine whether IHC is similar and to assess the cost-benefit of IHC. Resection cases (2009-2013) with absent MLH1 and PMS2 and prior BRAF mutation polymerase chain reaction results were chosen (n = 57). To mimic biopsy specimens, tissue microarrays (TMAs) were constructed. In addition, available biopsies performed prior to the resection were available in 15 cases. BRAF V600E IHC was performed and graded on TMAs, available biopsy specimens, and whole-section slides. Mutation status was compared with IHC, and cost-benefit analysis was performed. BRAF V600E IHC was similar in TMAs, biopsy specimens, and whole-section slides, with only four (7%) showing discordance between IHC and mutation status. Using BRAF V600E IHC in our Lynch syndrome screening algorithm, we found a 10% cost savings compared with mutational analysis. BRAF V600E IHC was concordant between TMAs, biopsy specimens, and whole-section slides, suggesting biopsy specimens are as useful as whole sections. IHC remained cost beneficial compared with mutational analysis, even though more patients needed additional molecular testing to exclude Lynch syndrome.

Clinicopathologic correlations of the BRAFV600E mutation, BRAF V600E immunohistochemistry, and BRAF RNA in situ hybridization in papillary thyroid carcinoma

BackgroundThe BRAFV600E mutation is the most common genetic alteration in papillary thyroid carcinoma (PTC). The aim of this study is to analyze the clinicopathologic correlations of the BRAFV600E mutation, BRAF V600E immunohistochemistry (IHC) and BRAF RNA in situ hybridization (ISH) in PTC. MethodsThis study included 467 patients with PTC who underwent surgical resection. We studied the BRAFV600E mutation using real-time PCR and BRAF V600E and BRAF RNA ISH using tissue microarray (TMA). ResultsThe frequencies of a positive BRAFV600E mutation by real-time PCR, positive BRAF V600E IHC, and high BRAF RNA ISH were 84%, 86%, and 70%, respectively, in PTC. Conventional PTC had higher positive rates in all three tests than other histologic types. The BRAFV600E mutation, BRAF V600E IHC, low ΔCt, and high BRAF RNA ISH were significantly associated with lymph node metastasis. The BRAFV600E mutation was significantly associated with positive immunostaining for BRAF V600E mutant protein (P<0.001) overall, with high BRAF RNA ISH only in the follicular variant (P=0.035). No significant correlation was noted between BRAF V600E IHC and BRAF RNA ISH. The sensitivity of BRAF V600E IHC for the BRAFV600E mutation was 95%, and the specificity was 61% overall, 96% and 54% in the conventional type, and 85% and 70% in the follicular variant. ConclusionsOur results showed that positive BRAF V600E IHC significantly correlated with the BRAFV600E mutation. This suggests its clinical utility as a screening tool for the BRAFV600E mutation. In addition, a high BRAF RNA ISH score could be a candidate marker of aggressive behavior in BRAFV600E mutation-positive cases of PTC.

BRAF mutations in non-small cell lung cancer.

BRAF is a proto-oncogene encoding a serine/threonine protein kinase which promotes cell proliferation and survival. BRAF mutations are commonly seen in melanoma and papillary thyroid carcinoma. We aimed to investigate the prevalence and clinicopathological features of BRAF mutations in non-small cell lung cancer (NSCLC) cases submitted for routine mutation testing at our institution. Mutation analysis for BRAF, EGFR and KRAS was performed using Sequenom MassARRAY platform with OncoCarta panel v1.0. Pathological features were reviewed and immunohistochemistry for BRAF V600E was also performed. Seven out of 273 cases (2.6%) had BRAF mutations (three males and four females, median age 70 years, all smokers), with six adenocarcinomas and one NSCLC, not otherwise specified (NOS). All had wild-type EGFR and KRAS. The identified BRAF mutations were V600E (4/7, 58%), K601N, L597Q and G469V. BRAF V600E immunohistochemistry was positive in two cases with V600E and negative in one case with K601N (tissue available in three cases only). No significant difference in age or gender was found (BRAF mutant vs. wild-type). BRAF mutations occur in a small proportion of NSCLC that lack other driver mutations. The clinicopathological profile differs from that of EGFR mutant tumours. The potential benefits of BRAF-inhibitors should be investigated.