Alterations of the BRAF gene in thyroid tumors

BRAF belongs to the RAF family of protein kinases that are important components of the MAPK signaling pathway mediating cell growth, differentiation and survival. Activating point mutation of the BRAF gene resulting in V600E (previously designated as V599E) is a common event in thyroid papillary carcinoma, being found in approx 40% of this tumor. It has strong association with classical papillary carcinoma and tall cell and possibly Warthin-like variants. This mutation also occurs in thyroid poorly differentiated and anaplastic carcinomas, usually those containing areas of papillary carcinoma. Alterations in the BRAF gene do not overlap with RAS mutations and RET/PTC rearrangement, indicating that activation of one of the effectors of the MAPK pathway is sufficient for papillary thyroid carcinogenesis. Recently, another mechanism of BRAF activation has been identified, which involves chromosome 7q inversion that results in the AKAP9-BRAF fusion. It is rare in sporadic papillary carcinomas and is more common in tumors associated with radiation exposure. Yet another mechanism of BRAF activation may involve copy number gain, which is seen in a significant portion of thyroid follicular tumors of both conventional and oncocytic (Hürthle cell) types.     

BRAF copy number gains in thyroid tumors detected by fluorescence In Situ hybridization

Point mutation of the BRAF gene is a common genetic event in papillary thyroid carcinomas. More recently, it has been found that BRAF can also participate in chromosomal rearrangement. In this study, we explore yet another possible mechanism of BRAF alteration, which involves copy number gain. Using fluorescence in situ hybridization with BRAF specific and chromosome 7 centromeric probes, we studied 62 follicular thyroid tumors and 32 papillary carcinomas. We found that numerical changes in BRAF copy number were rare in papillary thyroid carcinomas, while they occurred in 16–45% of follicular tumors of conventional and oncocytic (Hürthle cell) types. They were due to amplification of the gene or gain of one or more copies of chromosome 7. Tetrasomy for chromosome 7 was overall the most common finding. The changes in BRAF copy number did not overlap with RAS mutations in follicular tumors. In a group of follicular carcinomas, tumors with BRAF copy number gain were significantly more often widely invasive (67%) compared to tumors with no copy number change (18%). By Western blotting, the tumors carrying four copies of the gene revealed higher expression of BRAF protein, suggesting that copy number gain may represent another mechanism of BRAF activation in thyroid tumors.     

Aberrant BRAF splicing as an alternative mechanism for oncogenic B‐Raf activation in thyroid carcinoma

Activating BRAF mutations have recently been reported in 28–83% of papillary thyroid carcinomas (PTCs). However, it is not known whether aberrant BRAF splicing occurs in thyroid carcinoma. To investigate aberrant BRAF splicing and its association with BRAF mutation in thyroid tumours, we studied aberrant BRAF splicing and BRAF mutation from 68 thyroid tumours. BRAF^V600E mutation was detected in 20 of 43 PTCs and all three anaplastic thyroid carcinomas (ATCs). There is a higher frequency of BRAF mutation in PTC patients with stage III and IV tumours compared with stage I and II. Novel BRAF splicing variants were detected in 12 PTCs, three follicular variants of PTC (FVPTCs), and one ATC, as well as in two thyroid carcinoma cell lines, ARO and NPA. These variants did not have the N‐terminal auto‐inhibitory domain of wild‐type B‐Raf, resulting in an in‐frame truncated protein that contained only the C‐terminal kinase domain and caused constitutive activation of B‐Raf. These variants were significantly associated with advanced disease stage and BRAF^V600E mutation (p < 0.001, Fisher exact test). Furthermore, expression of these variants in NIH3T3 and CHO cells could activate the MAP kinase signalling pathway, transform them in vitro, and induce tumours in nude mice. These data suggest that BRAF splicing variants may function as an alternative mechanism for oncogenic B‐Raf activation. Combination of the BRAF^V600E mutation and its splicing variants may contribute towards disease progression to poorly differentiated thyroid carcinoma. Copyright © 2008 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.     

Enhanced B-Raf protein expression is independent of V600E mutant status in thyroid carcinomas

BRAF (7q24) encodes a serine/threonine protein kinase, and its expression level varies in different tissues. Although a high prevalence of BRAF mutation has been suggested as an important event in thyroid tumorigenesis, little is known about the expression pattern of B-Raf in the thyroid. Thus, we examined the expression of B-Raf in various neoplastic and nonneoplastic thyroid tissues and compared it with BRAF mutational status. Normal and hyperplastic thyroid tissues showed focal and faint immunoreactivity for B-Raf, especially in cuboidal follicular cells of small follicles. In contrast, diffuse expression of B-Raf was observed in follicular adenomas and well-differentiated carcinomas. The missense point mutation BRAF(V600E) was identified in 42% (13/31 cases) of papillary carcinomas and 33% (5/15 cases) of undifferentiated carcinomas but not in normal thyroid tissues, nodular hyperplasia, follicular adenomas, or follicular carcinomas. The immunohistochemical expression of B-Raf did not correlate with BRAF mutational status. Moreover, Western blotting revealed that B-Raf expression in thyroid carcinoma cell lines was also independent of BRAF mutation. Serum or fibroblast growth factor-1 stimulation further activates ERK1/2 in heterozygous BRAF(V600E)-positive carcinoma cells as well as BRAF(V600E) mutation-negative carcinoma cells. In conclusion, heterogeneous focal expression of wild-type B-Raf in nonneoplastic tissues may play a role in the growth or functional activity of thyroid follicular cells. In contrast, diffuse expression of wild-type and/or mutant B-Raf may be involved in the tumorigenic process resulting in activation of the mitogen-activated protein kinase signaling pathway in cooperation with other genetic abnormalities and activation of ligand-receptor signaling pathways.     

<Emphasis Type="Italic">BRAF</Emphasis> mutations typical of papillary thyroid carcinoma are more frequently detected in undifferentiated than in insular and insular-like poorly differentiated carcinomas

Somatic mutations of the BRAF gene (BRAF^V599E and BRAF^K600E) were found to be closely associated with different histotypes of papillary thyroid carcinoma (PTC). The V599E mutation is highly prevalent in PTC with a papillary or mixed papillary follicular growth pattern, and the K600E mutation is apparently restricted to the follicular variant of PTC. It is usually accepted that thyroid malignancies may follow a progression path from well-differentiated to poorly differentiated (PDC) and undifferentiated (UC) carcinomas. One would expect that at least some of the less differentiated carcinomas would harbour the genetic alterations of pre-existing well-differentiated tumours. In order to find the prevalence of BRAF mutations in PDC and UC, we screened a series of 19 PDCs and 17 UCs, as well as 3 UC-derived cell lines, for both mutation types. The group of PDCs was restricted to the so-called insular and insular-like PDCs, thus excluding PTCs with solid, insular or trabecular foci of growth and PDCs displaying typical PTC nuclei. No BRAF mutations were detected in any of the 19 cases of PDC, whereas 6 of the UCs (35%) and one UC-derived cell line presented the BRAF^V599E mutation. The BRAF^K600E mutation was not detected in any case. We conclude that UC may progress from BRAF^V599E-mutated PTC. The absence of BRAF mutations in our series of PDC supports the assumption that pure insular and insular-like PDCs are more closely related to follicular carcinoma than to PTC.Paula Soares and Vítor Trovisco contributed equally to this work.     

Detection of BRAFV600E mutation on papillary thyroid carcinoma and metastatic malignant melanoma by fine‐needle aspiration cytology

A genetic link between cutaneous melanoma and thyroid cancer (TC) has been identified. A high percentage of both melanomas and papillary carcinomas of the thyroid harbors a recurrent mutation (i.e., BRAF^V600E) in the BRAF oncogene. Herein, we report the case of a 65‐year‐old man with papillary TC and cutaneous malignant melanoma metastatic to masseter muscle, both characterized by BRAF mutation. This is one of the rare reports in which a complete molecular characterization has been performed. As the patients with papillary thyroid carcinoma have a higher risk of malignant melanoma and vice versa, continuous monitoring of such patients, with either of these tumors is necessary. Fine‐needle aspiration cytology is useful as shown in the present case. Diagn. Cytopathol. 2014;42:877–879. © Wiley Periodicals, Inc.     

Association of BRAFV600E mutation with clinicopathological features of papillary thyroid carcinoma: a study on a Chinese population

Background: The new finding of the heterogeneous distribution of BRAF^V600E mutation in primary papillary thyroid carcinoma suggested the percentage of BRAF^V600E alleles should be taken into consideration when evaluating its association with clinicopathological features of papillary thyroid carcinoma. The aim of this study was to detect both the presence and the percentage of BRAF^V600E alleles in fine-needle aspiration biopsy samples and to assess its association with clinicopathological characteristics of papillary thyroid carcinoma in a Chinese population. Materials and methods: Fine needle aspiration samples were collected in a total of 182 patients (132 conventional papillary thyroid carcinomas and 50 goiters). The associations of the presence and percentage of BRAF^V600E alleles genotyped by pyrosequencing with clinicopathological characteristics were evaluated in papillary thyroid carcinomas. Results: 80 (60.61%) of papillary thyroid carcinomas exhibited BRAF^V600E mutation in a range of 7.7% to 46.3% of the total BRAF alleles. The presence of BRAF^V600E mutation was significantly associated with extrathyroidal invasion. There was no significant difference between the presence of BRAF^V600E mutation and other clinicopathological features. It was not found that the significant relationship between percentage of BRAF^V600E alleles and clinicopathological characteristics. Conclusion: We concluded that the presence of BRAF^V600E could be preoperatively predictive of extrathyroidal invasion in a Chinese population.     

A Novel Complex BRAF Mutation Detected in a Solid Variant of Papillary Thyroid Carcinoma

BRAF gene mutations are identified in about 45% of papillary thyroid carcinomas (PTC) and represent the most common genetic event in this tumor. Here, we report a case of PTC, solid variant, with a complex BRAF mutation that involves one nucleotide substitution, C1796T, and a CTT triplet insertion, 1798_1799insCTT, located on the same allele. This mutation leads to the replacement of a threonine with an isoleucine, T599I, and replacement of a valine with an alanine and a leucine, V600delinsAL. This mutation was identified both in the preoperative fine needle aspirate sample and in the surgical specimen after total thyroidectomy. Other rare BRAF mutations in PTC are reviewed.     

Correlation between BRAF mutation and the clinicopathological parameters in papillary thyroid carcinoma with particular reference to follicular variant

Mutation of the BRAF gene is common in thyroid cancer. Follicular variant of papillary thyroid carcinoma is a variant of papillary thyroid carcinoma that has created continuous diagnostic controversies among pathologists. The aims of this study are to (1) investigate whether follicular variant of papillary thyroid carcinoma has a different pattern of BRAF mutation than conventional papillary thyroid carcinoma in a large cohort of patients with typical features of follicular variant of papillary thyroid carcinoma and (2) to study the relationship of clinicopathological features of papillary thyroid carcinomas with BRAF mutation. Tissue blocks from 76 patients with diagnostic features of papillary thyroid carcinomas (40 with conventional type and 36 with follicular variant) were included in the study. From these, DNA was extracted and BRAF V600E mutations were detected by polymerase chain reaction followed by restriction enzyme digestion and sequencing of exon 15. Analysis of the data indicated that BRAF V600E mutation is significantly more common in conventional papillary thyroid carcinoma (58% versus 31%, P = .022). Furthermore, the mutation was often noted in female patients (P = .017), in high-stage cancers (P = .034), and in tumors with mild lymphocytic thyroiditis (P = .006). We concluded that follicular variant of papillary thyroid carcinoma differs from conventional papillary thyroid carcinoma in the rate of BRAF mutation. The results of this study add further information indicating that mutations in BRAF play a role in thyroid cancer development and progression.     

BRAF V600E mutation detection by immunohistochemistry in colorectal carcinoma

The serine/threonine‐protein kinase B‐raf (BRAF) is an oncogene mutated in various neoplasms, including 5–15% of colorectal carcinomas. The T1799A point mutation, responsible for a large majority of these alterations, results in an amino acid substitution (V600E) causing the constitutive activation of a protein kinase cascade. BRAF V600E in MLH1 deficient tumors implicates somatic tumor‐only methylation of the MLH1 promoter region instead of a germline MLH1 mutation. BRAF V600E also predicts poor prognosis in microsatellite stable colorectal cancers and may be a marker of resistance to anti‐EGFR therapy in metastatic disease. Currently, only molecular methods are available for assessing BRAF mutational status. An immunohistochemical approach is evaluated here. Colon cancers from 2008 to 2012 tested by pyrosequencing for BRAF V600E mutation were selected. A total of 31 tumors with (n = 14) and without (n = 17) the BRAF V600E mutation were analyzed by immunohistochemistry using a commercially available antibody specific to the V600E‐mutated protein. All 14 colorectal carcinomas with the BRAF V600E mutation demonstrated cytoplasmic positivity in tumor cells with the anti‐BRAF antibody. In a minority of cases, staining intensity for the mutated tumor samples was weak (n = 2) or heterogeneous (n = 4); however, the majority of cases showed diffuse, strong cytoplasmic positivity (8 of 14 cases). None of the 17 BRAF wild‐type colorectal cancers showed immunoreactivity to the antibody. The overall sensitivity and specificity of the immunohistochemical BRAF V600E assay was 100%. Detection of the BRAF V600E mutation in colorectal cancer by immunohistochemistry is a viable alternative to molecular methods. © 2013 Wiley Periodicals, Inc.     

Germline mutation in BRAF codon 600 is compatible with human development: de novo p.V600G mutation identified in a patient with CFC syndrome

Champion KJ, Bunag C, Estep AL, Jones JR, Bolt CH, Rogers RC, Rauen KA, Everman DB. Germline mutation in BRAF codon 600 is compatible with human development: de novo p.V600G mutation identified in a patient with CFC syndrome. BRAF, the protein product of BRAF, is a serine/threonine protein kinase and one of the direct downstream effectors of Ras. Somatic mutations in BRAF occur in numerous human cancers, whereas germline BRAF mutations cause cardio‐facio‐cutaneous (CFC) syndrome. One recurrent somatic mutation, p.V600E, is frequently found in several tumor types, such as melanoma, papillary thyroid carcinoma, colon cancer, and ovarian cancer. However, a germline mutation affecting codon 600 has never been described. Here, we present a patient with CFC syndrome and a de novo germline mutation involving codon 600 of BRAF, thus providing the first evidence that a pathogenic germline mutation involving this critical codon is not only compatible with development but can also cause the CFC phenotype. In vitro functional analysis shows that this mutation, which replaces a valine with a glycine at codon 600 (p.V600G), leads to increased ERK and ELK phosphorylation compared to wild‐type BRAF but is less strongly activating than the cancer‐associated p.V600E mutation.     

<Emphasis Type="Italic">BRAF</Emphasis><Superscript>V600E</Superscript> Mutation in Papillary Thyroid Carcinoma: Significant Association with Node Metastases and Extra Thyroidal Invasion

B-Raf (BRAF) is the strongest activator in the downstream of MAP kinase signaling. The somatic point mutation of BRAF gene (V600E) is the most common and specific event in papillary thyroid carcinoma (PTC). However, its prevalence is variable among different studies and its association with clinico-pathological features is controversial. This study tests the prevalence of BRAF ^V600E mutation in thyroid cancer patients in Indian subcontinental population. We analyzed 140 thyroid tumor specimens for BRAF gene mutation at codon 600 using mutant-allele-specific amplification, single-strand conformation polymorphism, Mutector assay, and DNA sequencing of the PCR-amplified exon 15. BRAF mutation at codon 600 was detected in 46 of 86 PTC patients (53.4%) from Indian subcontinental cohort. Frequency of mutation varied across the subtypes of PTCs. BRAF ^V600E mutation was more common in the conventional PTC (38 out of 62; 61%) than in the follicular variant of PTC (2 out of 17; 11.7%). None of the 8 follicular thyroid adenomas, 14 follicular thyroid carcinomas, 16 medullary thyroid carcinomas, and 16 benign hyperplasia patients showed any exon 15 mutation. We found significant correlation between BRAF mutation status and extra-thyroidal invasion, lymph node metastasis, and tumor stage. However no correlation was observed with gender, age, and tumor size of the patients. Thus our findings suggest that BRAF ^V600E is a prevalent genetic alteration in adult sporadic PTCs in Indian cohort and it may be responsible for the progression of classic variant of PTC to metastatic and poorly differentiated subtype and likely to have significant impact on its diagnostic and prognostic management.     

Genetic alterations involved in the transition from well-differentiated to poorly differentiated and anaplastic thyroid carcinomas

Recent molecular studies have provided new insights into thyroid carcinogenesis. In thyroid papillary carcinomas at least three initiating events may occur, which are point mutations in the BRAF and RAS genes and RET/PTC rearrangements. Tumors harboring mutant BRAF and RAS are prone to progression to poorly differentiated and anaplastic carcinoma, but most likely require additional mutations to trigger this process. In thyroid follicular carcinomas, two known initiating events are RAS mutations and PAX8-PPARγ rearrangements, and RAS predisposes to dedifferentiation of follicular carcinomas. p53 and β-catenin mutations, found with increasing incidence in poorly differentiated and anaplastic carcinomas but not in well-differentiated tumors, may serve as a direct molecular trigger of tumor dedifferentiation. Additional evidence for progression from a preexisting well-differentiated carcinoma to poorly differentiated and anaplastic carcinoma comes from the studies of loss of heterozygosity and comparative genomic hybridization. Molecular studies, although limited by the lack of uniform histologic criteria for poorly differentiated carcinomas, revealed no genetic mutations or chromosomal abnormalities that are unique for poorly differentiated carcinoma and not present in well-differentiated or anaplastic carcinomas. This suggests that poorly differentiated carcinoma, as a group, represents a distinct step in the evolution from well-differentiated to anaplastic thyroid carcinoma, rather than an entirely separate type of thyroid malignancy.     

Mutational activation of BRAF is not a major event in sporadic childhood papillary thyroid carcinoma.

Papillary thyroid carcinoma may encompass a mixed group of neoplasms where divergence in clinical behavior may reflect distinct genetic alterations. For example, young patients with papillary thyroid carcinoma have a better prognosis than affected adults, and their carcinomas are much more likely to harbor chromosomal rearrangements involving the RET proto-oncogene. Mutational activation of the BRAF oncogene has recently been identified as the most common genetic alteration in papillary thyroid carcinoma, but little is known about its frequency as a function of patient age. We tested 20 papillary thyroid carcinomas from young patients ranging from 10 to 17 years of age for the thymine (T) --> adenine (A) missense mutation at nucleotide 1796 in the BRAF gene using a newly developed assay that employs a novel primer extension method (Mutector assay). The prevalence of BRAF mutation was compared with a larger group of papillary thyroid carcinomas from previously tested adult patients (>20 years). BRAF mutations were not common in papillary thyroid carcinomas from young patients compared to their counterparts in adults (20 vs 77%; OR=13.3, 95% confidence interval (CI)=3.4-56.5; P<0.0001), but they become increasingly prevalent with advancing patient age (OR as a function of age at 10-year intervals=1.80 CI=1.33-2.44; P<0.001). Unlike papillary thyroid carcinomas that arise in adults, mutational activation of BRAF is not a major genetic alteration in papillary thyroid carcinomas that arise in young patients. The increasing frequency of BRAF mutations as a function of age could help account for the well documented but poorly understood observation that age is a relevant prognostic indicator for patients with papillary thyroid carcinoma.     

RAS Mutation-Positive Follicular Variant of Papillary Thyroid Carcinoma Arising in a Struma Ovarii

Struma ovarii is an ovarian mature teratoma composed exclusively or predominantly of thyroid tissue. Malignant transformation of struma ovarii is rare and poorly understood, although this process is thought to be similar to carcinogenesis in malignant tumors of differentiated thyroid tissue originating in the thyroid gland. Genetic alterations in the mitogen-activated protein kinase pathway, including mutations of BRAF, RAS, and RET genes, have been implicated in the development of differentiated thyroid carcinoma arising in the thyroid gland. We report here a case with RAS mutation detected in a malignant struma ovarii. The patient is a 38-year-old female who had a 2.4 cm ovarian cyst noted incidentally on a first trimester ultrasound. She proceeded to ovarian cystectomy post-delivery, with pathologic examination detecting a papillary thyroid carcinoma, follicular variant, arising in a cystic teratoma. The tumor was tested for BRAF, RAS, and RET/PTC mutations. HRAS codon 61 mutation was identified. This is the first report of RAS mutation detected in the follicular variant of papillary carcinoma arising in a struma ovarii. It provides evidence that tumors developing in this setting involve molecular mechanisms similar to those implicated in tumors developing in the thyroid gland.     

BRAF mutations in anaplastic thyroid carcinoma: implications for tumor origin, diagnosis and treatment.

Anaplastic thyroid carcinoma is a highly aggressive neoplasm. Affected patients typically present with advanced disease where there is little hope for cure using conventional therapeutic modalities. Understanding the genetic alterations underlying the development of anaplastic thyroid carcinoma, such as mutational activation of BRAF, could help clarify its relationship with well-differentiated forms of thyroid carcinoma (ie follicular and papillary carcinoma) and could help select patients most likely to benefit from novel therapeutic strategies targeting BRAF. We tested 16 anaplastic thyroid carcinomas for the thymine (T) --> adenine (A) missense mutation at nucleotide 1796 in the BRAF gene using a newly developed assay that employs a novel primer extension method (Mutector assay). Seven of these anaplastic thyroid carcinomas arose in association with a well-differentiated thyroid carcinoma, and these were also evaluated. The 1796T --> A mutation was detected in eight (50%) of the anaplastic thyroid carcinomas, in four of five (80%) associated papillary thyroid carcinomas, and in zero of two (0%) associated follicular carcinomas. In all seven cases where anaplastic thyroid carcinoma arose in association with a well-differentiated thyroid carcinoma, BRAF status in the two components was concordant. Like papillary thyroid carcinoma, a significant percentage of anaplastic thyroid carcinomas also harbor BRAF mutations. Indeed, when papillary thyroid carcinoma and anaplastic thyroid carcinoma occur together, they consistently share the same BRAF profile, supporting the notion that many anaplastic thyroid carcinomas actually represent progressive malignant degeneration of a pre-existing well-differentiated thyroid carcinoma. The high frequency of BRAF mutations in a tumor that is generally regarded as uniformly fatal justifies evaluation of the potential benefits of anti-BRAF therapy for patients with anaplastic thyroid carcinoma.     

Critical Pitfalls in the use of <Emphasis Type="Italic">BRAF</Emphasis> Mutation as a Diagnostic Tool in Thyroid Nodules: a Case Report

Thyroid fine-needle aspiration (FNA) cytology is the primary tool for the diagnostic evaluation of thyroid nodules. BRAF mutation analysis is employed as an ancillary tool in indeterminate cases, as recommended by the American Thyroid Association management guidelines. Hereby, we report the case of a 73-year-old woman who presented an 8-mm-size, ill-defined, left thyroid nodule. FNA resulted “suspicious for papillary thyroid carcinoma”. BRAF mutation status was analyzed, and somatic BRAF ^V600E mutation identified. The patient underwent a total thyroidectomy. At histological examination, the nodule was composed of Langerhans cells, admixed with many eosinophils. A final diagnosis of Langerhans cell histiocytosis of the thyroid was made. Our case emphasizes the critical diagnostic pitfalls due to the use of BRAF ^V600E mutation analysis in thyroid FNA. Notably, BRAF ^V600E mutation is common in melanoma, colorectal carcinoma, lung carcinoma, ovarian carcinoma, brain tumors, hairy cell leukemia, multiple myeloma, and histiocytoses. Therefore, in cases of indeterminate FNA with unclassifiable atypical cells BRAF ^V600E mutated, the possibility of a localization of hystiocytosis or a secondary thyroid malignancy should be taken into account.     

BRAF(V600E) mutation analysis of liquid-based preparation-processed fine needle aspiration sample improves the diagnostic rate of papillary thyroid carcinoma

Early detection and diagnosis of papillary thyroid carcinoma are important for successful management of patients. Liquid-based preparations (Thinprep) of fine needle aspirations from thyroid nodules are now widely used and are replacing conventional smears because residual samples can be used for ancillary tests. Detection of the BRAF(V600E) mutation in cytology specimens could aid in the diagnosis of papillary thyroid carcinoma. We, therefore, analyzed the cytologic features and BRAF(V600E) mutation status of thyroid liquid-based preparation-fine needle aspiration samples. A total of 191 histologically confirmed thyroid liquid-based preparation-fine needle aspiration specimens were selected. We analyzed cytomorphological features and BRAF(V600E) mutation status in both liquid-based preparation-fine needle aspiration samples and the corresponding formalin-fixed, paraffin-embedded tissues. The Seeplex BRAF ACE detection kit (Seoul, Korea), melting curve analysis with SYBR green, and sequencing analysis were used to detect BRAF(V600E) mutations. Of 191 patients, 126 had histologically confirmed papillary thyroid carcinoma, whereas the remaining 65 lesions were benign lesions and carcinomas of other types. The sensitivity of liquid-based preparation alone for diagnosis of papillary thyroid carcinoma was 71.4%. When BRAF(V600E) mutation analyses results were considered in conjunction with the cytologic diagnosis, the diagnostic sensitivity for detecting papillary thyroid carcinoma increased to 84.9% regardless of the method used to detect BRAF mutations. BRAF(V600E) mutation analysis using residual liquid-based preparation cytologic samples is, therefore, a powerful additional diagnostic tool for diagnosis of papillary thyroid carcinoma.     

BRAF mutation is unusual in chronic lymphocytic thyroiditis-associated papillary thyroid carcinomas and absent in non-neoplastic nuclear atypia of thyroiditis

Chronic lymphocytic thyroiditis (CLT) has an epidemiological relationship to papillary thyroid carcinoma (PTC). The follicular epithelium in CLT can be markedly atypical, with cytologic changes ranging from oncocytic morphology to clearing and overlapping. At the molecular level, the association between CLT and PTC is more controversial. In order to further characterize the molecular changes in CLT, this study examined the BRAF gene in 27 patient samples with CLT and without carcinoma and 28 samples with CLT and carcinoma (12 conventional papillary carcinomas, 13 follicular variants, and 3 tall cell variants). Microdissection, PCR, and sequencing of exon 15 of the BRAF gene were performed. BRAF mutations were uncommon in the cases studied with only two microscopic and two clinically sized PTCs had BRAF mutations (14%). There was no evidence of BRAF mutation in any of the areas with atypical follicular epithelium in CLT. These data suggest that BRAF is a less frequent mechanism of tumorigenesis in a background of CLT and that BRAF mutation is not present in the atypical follicular epithelium of CLT.