BRAF(V600E) mutation analysis from May-Grünwald Giemsa-stained cytological samples as an adjunct in identification of high-risk papillary thyroid carcinoma

Romanowsky staining: history, recent advances and future prospects from a chemistry perspective

Romanowsky staining was an important methodological breakthrough in diagnostic hematology and cytopathology during the late 19th and early 20th centuries; it has facilitated for decades the work of biologists, hematologists and pathologists working with blood cells. Despite more than a century of studying Romanowsky staining, no systematic review has been published that explains the chemical processes that produce the "Romanowsky effect" or "Romanowsky-Giemsa effect" (RGE), i.e., a purple coloration arising from the interaction of an azure dye with eosin and not due merely to their simultaneous presence. Our review is an attempt to build a bridge between chemists and biomedical scientists and to summarize the available data on methylene blue (MB) demethylation as well as the related reduction and decomposition of MB to simpler compounds by both light and enzyme systems and microorganisms. To do this, we analyze modern data on the mechanisms of MB demethylation both in the presence of acids and bases and by disproportionation due to the action of light. We also offer an explanation for why the RGE occurs only when azure B, or to a lesser extent, azure A is present by applying experimental and calculated physicochemical parameters including dye-DNA binding constants and electron density distributions in the molecules of these ligands. Finally, we discuss modern techniques for obtaining new varieties of Romanowsky dyes by modifying previously known ones. We hope that our critical literature study will help scientists understand better the chemical and physicochemical processes and mechanisms of cell staining with such dyes.

Molecular markers for the classification of cytologically indeterminate thyroid nodules

BACKGROUND

The diagnosis of indeterminate lesions of the thyroid is a challenge in cytopathology practice. Indeed, up to 30% of cases lack the morphological features needed to provide definitive classification. Molecular tests have been developed to assist in the diagnosis of these indeterminate cases. The first studies dealing with the preoperative molecular evaluation of FNA samples focused on the analysis of BRAF^V600E or on the combined evaluation of two or three genetic alterations. The sensitivity of molecular testing was then improved through the introduction of gene panels, which became available for clinical use in the late 2000s. Two different categories of molecular tests have been developed, the 'rule-out' methods, which aim to reduce the avoidable treatment of benign nodules, and the 'rule-in' tests that have the purpose to optimize surgical management. The genetic evaluation of indeterminate thyroid nodules is predicted to improve patient care, particularly if molecular tests are used appropriately and with the awareness of their advantages and weaknesses. The main disadvantage of these tests is the cost, which makes them rarely used in Europe. To overcome this limitation, customized panels have been set up, which are able to detect the most frequent genetic alterations of thyroid cancer.

CONCLUSIONS

In the present review, the most recent available versions of commercial molecular tests and of custom, non-commercial panels are described. Their characteristics and accuracy in the differential diagnosis of indeterminate nodules, namely Bethesda classes III (Atypical follicular lesion of undetermined significance, AUS/FLUS) and IV (Suspicious for follicular neoplasm, FN/SFN) are fully analyzed and discussed.

Molecular Variants and Their Risks for Malignancy in Cytologically Indeterminate Thyroid Nodules

Background: Gene panels are routinely used to assess predisposition to hereditary cancers by simultaneously testing multiple susceptibility genes and/or variants. More recently, genetic panels have been implemented as part of solid tumor malignancy testing assessing somatic alterations. One example is targeted variant panels for thyroid nodules that are not conclusively malignant or benign upon fine-needle aspiration (FNA). We systematically reviewed published studies from 2009 to 2018 that contained genetic data from preoperative FNA specimens on cytologically indeterminate thyroid nodules (ITNs) that subsequently underwent surgical resection. Pooled prevalence estimates per gene and variant, along with their respective positive predictive values (PPVs) for malignancy, were calculated. Summary: Our systematic search identified 540 studies that were supplemented by 18 studies from bibliographies or personal files. Sixty-one studies met all inclusion criteria and included >4600 ITNs. Overall, 26% of nodules contained at least 1 variant or fusion. However, half of them did not include details on the specific gene, variant, and/or complete fusion pair reported for inclusion toward PPV calculations. The PPVs of genomic alterations reported at least 10 times were limited to BRAF^V600E (98%, 95% confidence interval [CI 96-99%]), PAX8/PPARG (55% [CI 34-78%]), HRAS^Q61R (45% [CI 22-72%]), BRAF^K601E (42% [CI 19-68%]), and NRAS^Q61R (38% [CI 23-55%]). Excluding BRAF^V600E, the pooled PPV for all other specified variants and fusions was 47%. Multiple variants within the same nodule were identified in ∼1% of ITN and carried a cumulative PPV of 77%. Conclusions: The chance that a genomic alteration predicts malignancy depends on the individual variant or fusion detected. Only five alterations were reported at least 10 times; BRAF^V600E had a PPV of 98%, while the remaining four had individual PPVs ranging from 38% to 55%. The small sample size of most variants and fusion pairs found among ITNs, however, limits confidence in their individual PPV point estimates. Better specific reporting of genomic alterations with cytological category, histological subtype, and cancer staging would facilitate better understanding of cancer prediction, and the independent contribution of the genomic profile to prognosis.

Clinical impact of a cytological screening system using cyclin D1 immunostaining and genomic analysis for the diagnosis of thyroid nodules

Background

Fine-needle aspiration (FNA) is the most reliable method for diagnosing thyroid nodules; however, some features such as atypia of undetermined significance or follicular lesion of undetermined significance can confound efforts to identify malignancies. Similar to BRAF, cyclin D1 may be a strong marker of cell proliferation.

Methods

One hundred two patients with thyroidal nodule were enrolled in this prospective study.

Expression of cyclin D1 in thyroid nodules was determined by immunohistochemistry using both surgical specimens and their cytological specimens. The identification of the optimal cut off points for the diagnosis of malignancy were evaluated using the receiver operating characteristic (ROC) curves and the assessment of the area under the ROC curve (AUC). The specificity, sensitivity, positive predictive value (PPV) of markers were evaluated from crosstabs based on cut off points and significance were calculated. We also analyzed genetic variants by target NGS for thyroid nodule samples.

Results

The positive predictive value (PPV) and median stain ratio (MSR) of cyclin D1 nuclear staining was determined in papillary thyroid carcinoma (PPV = 91.5%, MSR = 48.5%), follicular adenoma (PPV = 66.7%, MSR = 13.1%), and adenomatous goiter and inflammation controls (MSR = 3.4%). In FNA samples, a threshold of 46% of immunolabelled cells allows to discriminate malignant lesions from benign ones (P < 0.0001), with 81% sensitivity and 100% specificity. A 46% cutoff value for positive cyclin D1 immunostaining in thyroid cells demonstrated 81% sensitivity and 100% specificity. In surgical specimens, ROC curve analysis showed a 5.8% cyclin D1 immunostaining score predicted thyroid neoplasms at 94.4% sensitivity and 92.3% specificity (P = 0.003), while a 15.7% score predicted malignancy at 86.4% sensitivity and 80.5% specificity (P < 0.0001). Finally, three tested clinico-pathological variables (extra thyroidal extension, intraglandular metastasis, and lymph node metastasis) were significant predictors of cyclin D1 immunostaining (P < 0.001).

Conclusion

Our cytological cyclin D1 screening system provides a simple, accurate, and convenient diagnostic method in precision medicine enabling ready determination of personalized treatment strategies for patients by next generation sequencing using cytological sample.

Electronic supplementary material

The online version of this article (10.1186/s12885-019-5452-4) contains supplementary material, which is available to authorized users.

Molecular testing in the diagnosis of differentiated thyroid carcinomas

Different genetic mutations and other molecular alterations in papillary thyroid cancer (PTC) and follicular thyroid cancer (FTC) can be detected in fine-needle aspiration (FNA) of thyroid nodules, and can be used successfully to ameliorate cancer diagnosis and management of patients with thyroid nodules. The greatest experience has been obtained with the diagnostic use of BRAF mutation that is strongly specific for malignancy when detected using well-validated techniques. The strongest diagnostic result can be obtained testing FNA samples for a panel of mutations that typically involve TERT, BRAF, PAX8/PPARγ, RAS, and RET/PTC. Finding any of these mutations in a thyroid nodule provides strong indication for malignancy and helps to refine clinical management for a significant proportion of patients with indeterminate cytology. The use of molecular markers, as TERT, BRAF, PAX8/PPARγ, RAS, and RET/PTC, may be considered for patients with indeterminate FNA cytology (FNAC) to help guide management. In patients with indeterminate TIR3 FNA, the combination of precise molecular marker expression analysis with molecular mutations evaluations could ameliorate significantly the accuracy of cancer diagnosis. However other prospective studies are needed to identify more accurate molecular markers. Finally, the knowledge of these molecular pathways has permitted the development of new targeted therapies for aggressive TC.

Diagnostic Utility of Molecular and Imaging Biomarkers in Cytological Indeterminate Thyroid Nodules

Indeterminate thyroid cytology (Bethesda III and IV) corresponds to follicular-patterned benign and malignant lesions, which are particularly difficult to differentiate on cytology alone. As ~25% of these nodules harbor malignancy, diagnostic hemithyroidectomy is still custom. However, advanced preoperative diagnostics are rapidly evolving.This review provides an overview of additional molecular and imaging diagnostics for indeterminate thyroid nodules in a preoperative clinical setting, including considerations regarding cost-effectiveness, availability, and feasibility of combining techniques. Addressed diagnostics include gene mutation analysis, microRNA, immunocytochemistry, ultrasonography, elastosonography, computed tomography, sestamibi scintigraphy, [18F]-2-fluoro-2-deoxy-d-glucose positron emission tomography (FDG-PET), and diffusion-weighted magnetic resonance imaging.The best rule-out tests for malignancy were the Afirma® gene expression classifier and FDG-PET. The most accurate rule-in test was sole BRAF mutation analysis. No diagnostic had both near-perfect sensitivity and specificity, and estimated cost-effectiveness. Molecular techniques are rapidly advancing. However, given the currently available techniques, a multimodality stepwise approach likely offers the most accurate diagnosis, sequentially applying one sensitive rule-out test and one specific rule-in test. Geographical variations in cytology (e.g., Hürthle cell neoplasms) and tumor genetics strongly influence local test performance and clinical utility. Multidisciplinary collaboration and implementation studies can aid the local decision for one or more eligible diagnostics.

Diagnostic value of BRAF (V600E)-mutation analysis in fine-needle aspiration of thyroid nodules: a meta-analysis

Fine-needle aspiration (FNA) is a reliable method for preoperative diagnosis of thyroid nodules; however, about 10%–40% nodules are classified as indeterminate. The BRAF^V600E mutation is the most promising marker for thyroid FNA. This meta-analysis was conducted to investigate the diagnostic value of BRAF^V600E analysis in thyroid FNA, especially the indeterminate cases. Systematic searches were performed in PubMed, Web of Science, Scopus, Ovid, Elsevier, and the Cochrane Library databases for relevant studies prior to June 2015, and a total of 88 studies were ultimately included in this meta-analysis. Compared with FNA cytology, the synergism of BRAF^V600E testing increased the diagnostic sensitivity from 81.4% to 87.4% and decreased the false-negative rate from 8% to 5.2%. In the indeterminate group, the mutation rate of BRAF^V600E was 23% and varied in different subcategories (43.2% in suspicious for malignant cells [SMC], 13.77% in atypia of undetermined significance/follicular lesion of undetermined significance [AUS/FLUS], and 4.43% in follicular neoplasm/suspicious for follicular neoplasm [FN/SFN]). The sensitivity of BRAF^V600E analysis was higher in SMC than that in AUS/FLUS and FN/SFN cases (59.4% vs 40.1% vs 19.5% respectively), while specificity was opposite (86.1% vs 99.5% vs 99.7% respectively). The areas under the summary receiver-operating characteristic curve also confirmed the diagnostic value of BRAF^V600E testing in SMC and AUS/FLUS rather than FN/SFN cases. Therefore, BRAF^V600E analysis can improve the diagnostic accuracy of thyroid FNA, especially indeterminate cases classified as SMC, and select malignancy to guide the extent of surgery.

FNA smears as a potential source of DNA for targeted next-generation sequencing of lung adenocarcinomas

BACKGROUND

Diff-Quik-stained fine-needle aspiration (FNA) smears and touch preparations from biopsies represent alternative specimens for molecular testing when cell block or biopsy material is insufficient. This study describes the use of these samples for targeted next-generation sequencing (NGS) of primary and metastatic lung adenocarcinoma and reports the DNA quality and success rates of FNA smears versus other specimens from 1 year of clinical use.

METHODS

A validation set of 10 slides from 9 patients with prior clinical epidermal growth factor receptor (EGFR) Sanger sequencing and KRAS pyrosequencing (5 KRAS-positive/EGFR-negative and 4 KRAS-negative/EGFR-negative) underwent DNA extraction, quality assessment, and targeted NGS. Subsequently, lung adenocarcinoma specimens submitted for NGS solid tumor mutation panel testing in 1 calendar year (60 biopsies, 57 resections, 33 FNA cell blocks, 12 FNA smears, and 10 body fluid cell blocks) were reviewed for specimen adequacy, sequencing success, and DNA quality.

RESULTS

All 10 validation samples met the DNA quality threshold (delta Ct threshold < 8; range, -2.2 to 4.9) and yielded 0.5 to 22 μg of DNA. The KRAS and EGFR mutation status from FNA smears according to NGS was concordant with previous clinical testing for all 10 samples. In the 1-year review, FNA smears were 100% successful, and this suggested a performance equivalent to or better than the performance of established specimen types, including FNA cell blocks. DNA quality according to ΔCt was significantly better with FNA smears versus biopsies, resections, and FNA cell blocks.

CONCLUSIONS

FNA smears of lung adenocarcinomas are high-quality alternative specimens for a targeted NGS panel with a high success rate in clinical practice. Cancer Cytopathol 2016;124:406-14. © 2016 American Cancer Society.

Optimizing the DNA yield for molecular analysis from cytologic preparations

BACKGROUND

Cytology smears and cytospin preparations are increasingly being used for molecular testing. With these limited samples, optimizing tissue extraction to maximize the DNA yield is, therefore, critical. This study examined 2 common methods of tissue extraction and compared DNA yields from different types of glass slides.

METHODS

The H226 lung cancer cell line and 5 clinical samples of cellular effusions were used to prepare Diff-Quik-stained cytospins on 4 types of glass slides: fully frosted (FF), nonfrosted (NF), positively charged (PC), and silane-coated (SC). Tissue extraction was performed by either scalpel-blade scraping or cell lifting with the Pinpoint Slide DNA Isolation System (Zymo Research). DNA was extracted with the QIAamp DNA Mini Kit (Qiagen) and was quantified with the Quant-iT PicoGreen Kit (Life Technologies).

RESULTS

The DNA yield in cell-line cytospins was significantly lower from FF slides versus NF, PC, and SC slides with both scraping and cell-lifting methods. In addition, scraping yielded significantly more DNA than cell lifting (P = .005). DNA yields from 5 clinical effusion cases with FF and NF slides showed results similar to the results for cell-line samples, with scraping consistently yielding more DNA than cell lifting and with NF slides outperforming FF slides.

CONCLUSIONS

Optimizing the DNA yield extracted from cytology specimens maximizes the chances of successful molecular testing and is critical in cases of low or marginal cellularity. This study demonstrates the following: 1) scraping yields more DNA than cell lifting, and 2) NF slides yield more DNA than FF slides.

Molecular diagnostics of fine needle aspiration for the presurgical screening of thyroid nodules

"The incidence of thyroid cancer, the most common endocrine malignancy, is rising. The two most common types of thyroid cancer are papillary and follicular" thyroid carcinomas. "Fine-needle aspiration (FNA) of thyroid nodules" can permit to detect many genetic mutations and other molecular alterations, including RAS and BRAF point mutations, PAX8/peroxisome proliferator-activated receptor (PPAR)γ and "RET/PTC rearrangements, occurring in thyroid papillary and follicular carcinomas" (more than 70% of cases), which can be used successfully to improve the diagnosis "and the management of patients with thyroid nodules". The most extensive experience has been accumulated with "the diagnostic use of BRAF mutation", which is highly specific for malignancy. "Testing FNA samples for a panel of mutations" that typically includes RAS, BRAF, PAX8/PPARγ and RET/PTC could permit to achieve the biggest diagnostic impact. "The accuracy of cancer diagnosis in thyroid nodules could be improved significantly using these and other emerging molecular markers".

Caveolin-1 Expression in Papillary Thyroid Carcinoma

Objective

We aimed to investigate the role of caveolin-1 in papillary thyroid carcinoma pathogenesis.

Study Design

Case series with chart review.

Setting

Institute for the Application of Nuclear Energy.

Subjects and Methods

We evaluated the expression of caveolin-1 in papillary thyroid carcinoma (PTC) by Western blot (WB) and compared the findings with immunohistochemical (IHC) expression of both epithelial and stromal caveolin-1 on the corresponding histological specimens. The results were related to clinicopathological features and BRAF mutation status.

Results

Caveolin-1 expression was found in malignant thyroid epithelium and more abundantly in tumor stroma but varied in both compartments within and between PTC subtypes. Caveolin-1 expression in the epithelium was more intense in classical PTC than in the other histological types. On the contrary, stromal caveolin-1 expression was stronger in the follicular, solid, and trabecular PTC variants than in classical PTC. Trends for down-regulation of caveolin-1 expression in epithelium and up-regulation in stroma from the classical via follicular to the solid variant were observed. The relation of WB and IHC results with clinicopathological parameters showed lower caveolin-1 tissue content in BRAF mutated tumors ( P < .05), a positive correlation of epithelial caveolin-1 expression with lymph node metastasis ( P < .05), and a negative association of stromal caveolin-1 expression with the degree of neoplastic infiltration and BRAF status.

Conclusion

Altered expression of caveolin-1 in the thyroid epithelial and stromal compartments may be involved in the pathogenesis of PTC. The potential clinical significance of caveolin-1 expression, as well as its relation to BRAF mutation status, deserves further investigation.

BRAF mutations in papillary thyroid carcinoma and emerging targeted therapies (review)

Papillary thyroid carcinoma (PTC) is the most common histotype among the thyroid cancer types. Although PTC is a curable malignancy, many patients relapse after treatment. Thus, there is a need to identify novel factors involved in the pathogenesis of PTC that may be used as targets for new therapies. The MAPK pathway has been implicated in the pathogenesis of PTC. Therefore, in this review, we summarize the role of the BRAF V600E mutation in the development and progression of thyroid cancer. The cinical implication of this molecular abnormality is also discussed. It is evident that the detection of the BRAF V600E mutation is crucial in order to identify novel avenues for thyroid cancer treatment.