Uncommon BRAF mutations in the follicular variant of thyroid papillary carcinoma: New insights.

Mutational analysis is reshaping the practice of fine-needle aspiration cytology for the diagnosis of thyroid nodules. The v-Raf murine sarcoma viral oncogene homolog B1 (BRAF) valine (V) to glutamic acid (E) substitution at codon 600 (BRAF(V600E)) is the most effective diagnostic/prognostic marker and is used mainly for papillary thyroid carcinomas (PTCs). Although BRAF(V600E) represents 95% of all BRAF mutations, uncommon BRAF mutations have been identified in thyroid carcinomas. For the current study, the authors evaluated morphologic (plump pink cells and sickle-shaped nuclei) anti-BRAF(V600E) antibody (VE1) immunocytochemical and molecular findings of BRAF mutations in PTCs and in the follicular variant of PTC (FVPC). Between January 2013 and June 2014, there were 150 cytologic samples with surgical follow-up at the authors' institution. BRAF mutations, which were identified using liquid-based cytology, were classified into wild-type BRAF, BRAF(V600E), and uncommon BRAF mutations. All clinicopathologic correlations between BRAF and FVPCs were analyzed. Forty-four of 150 samples were identified as benign histologic lesions, and the authors focused on the 106 cytologic samples from patients who had malignant outcomes (60 PTCs and 46 FVPCs). The series included 16 follicular neoplasms, 36 samples diagnosed as suspicious of malignancy, and 54 samples diagnosed as positive for malignancy. The BRAF(V600E) mutation was detected in 17.4% of FVPCs and in 66.6% of PTCs, whereas uncommon BRAF mutations were detected only in FVPCs. Plump pink cells and VE1 expression were not identified in samples that had uncommon BRAF mutations. VE1 immunocytochemistry yielded positive results in all 36 samples that had the BRAF(V600E) mutation. Uncommon BRAF mutations were observed only in FVPCs and were linked to less aggressive behavior. Negative/weak VE1 expression was observed in both wild-type and uncommon BRAF mutations. The current investigation did not reveal any plump cells or morphologic BRAF findings in samples that had uncommon BRAF mutations. In the authors' experience, BRAF mutations detected by DNA methods were more accurate in identifying FVPCs.

Rossi ED ，Martini M ，Bizzarro T ，Capodimonti S ，Cenci T ，Lombardi CP ，Pontecorvi A ，Fadda G ，Larocca LM ... -  《-》

Morphological parameters able to predict BRAF(V600E) -mutated malignancies on thyroid fine-needle aspiration cytology: Our institutional experience.

The BRAF(V600E) mutation is the most common diagnostic/prognostic marker in papillary thyroid carcinoma (PTC). Its evaluation is typically performed with DNA-based techniques; nonetheless, a few articles have recently proposed the morphological prediction of BRAF(V600E) in histological PTCs. We investigated this morphological parameter in our cytological series. We re-analyzed all 72 cytohistological samples diagnosed as positive for malignancy (favoring PTC) on fine-needle aspiration cytology from January 2012 to December 2013. We included 22 male patients and 50 female patients. The cytological cases were processed with liquid-based cytology. We performed molecular analysis and immunocytochemistry for the VE1 BRAF(V600E) antibody. We reported 47 mutated cases and 25 wild-type (WT) cases with 100% cytohistological concordance. The cytological evaluations revealed plump cells (abundant eosinophilic cytoplasm and PTC nuclei) in all 47 mutated cases, with only 6 having a focal plump cell component (≤20% cells). Furthermore, 5 of the 25 WT cases showed focal plump cells. A distinctive sickle nuclear shape was found only in the mutated cases. VE1 yielded 100% positivity for all 24 mutated cases that were tested, including 3 cases with focal plump cells. We demonstrated that the BRAF(V600E) mutation might be predicted in cytological samples on the basis of some specific morphological features. Although the detection of plump cells (mainly focal) was also observed in WT cases, the detection of sickle-shaped nuclei provided the highest specificity and sensitivity as a predictive mutational parameter. These morphological features might be a valid tool for selecting cases for molecular analysis.

Rossi ED ，Bizzarro T ，Martini M ，Capodimonti S ，Fadda G ，Larocca LM ，Schmitt F ... -  《-》

BRAF (V600E) mutation analysis on liquid-based cytology-processed aspiration biopsies predicts bilaterality and lymph node involvement in papillary thyroid microcarcinoma.

Activating mutations in the valine-to-glutamic acid substitution at position 600 of the v-raf murine sarcoma viral oncogene homolog B1 (BRAF-1) gene are detected frequently in patients with papillary thyroid carcinoma (PTC). These mutations have been identified in approximately 29% to 69% of PTCs and in >80% of PTCs of the tall cell variant, whereas they have not been detected in benign lesions or in the majority of those (80%) with the follicular variant of PTC. The objective of the current study was to evaluate the role of liquid-based cytology (LBC) for the detection of BRAF mutations in the outcome of patients who have thyroid PTC measuring ≤ 1 cm and, hence, in guiding their clinical and surgical management. From October 2010 through June 2011, 230 consecutive cases were diagnosed as positive for malignancy on fine-needle aspiration cytology processed by LBC. Of these, 73 PTCs ≤ 1 cm underwent BRAF mutational analysis. The aspirated material was processed using an LBC technique. After DNA extraction of the residual material, BRAF mutation analysis was performed using a direct sequencing method. Fifty of 73 patients (68.5%) underwent surgery, and 34 of those patients (68%) had tumors that expressed a BRAF mutation (31 PTCs, including 11 tall cell variants and 3 follicular-variant PTCs). A significant association between BRAF mutation and bilaterality of cancer was observed (odds ratio, 0.077; P = .0007). BRAF mutation was associated significantly with lymph node involvement (odds ratio, 19; P = .0007) but not with extracapsular infiltration (odds ratio, 0.298; P = .179). The current results indicated that BRAF gene mutations can be identified successfully on LBC material and using other cytologic methods with high reproducibility, feasibility, and informative results. The presence of a BRAF mutation may preoperatively predict the behavior of microscopic PTC, suggesting a more aggressive surgical approach.

Rossi ED ，Martini M ，Capodimonti S ，Lombardi CP ，Pontecorvi A ，Vellone VG ，Zannoni GF ，Larocca LM ，Fadda G ... -  《-》

Detection of BRAFV600E mutation on fine needle aspiration specimens of thyroid nodule refines cyto-pathology diagnosis, especially in BRAF600E mutation-prevalent area.

Chung KW ，Yang SK ，Lee GK ，Kim EY ，Kwon S ，Lee SH ，Park DJ ，Lee HS ，Cho BY ，Lee ES ，Kim SW ... -  《CLINICAL ENDOCRINOLOGY》

BRAF mutation detection in indeterminate thyroid cytology specimens: underlying cytologic, molecular, and pathologic characteristics of papillary thyroid carcinoma.

BRAF mutations are highly specific for papillary thyroid carcinoma (PTC) and many cytology specimens with BRAF mutations are expected to demonstrate cytologic features typical of PTC. However, indeterminate thyroid cytology cases are inevitable and understanding the significance of the BRAF mutation within the context of the Bethesda System for Reporting Thyroid Cytopathology would be valuable. Thyroid cytology cases submitted for conventional cytomorphologic evaluation and BRAF mutational analyses were selected from the authors' cytopathology files from April 2007 to October 2011. From this group, the diagnostic usefulness of BRAF mutations in indeterminate and malignant cases was assessed and analyses of cytologic and histopathologic features associated with the mutations in this gene were performed. A total of 131 cases with a BRAF mutation were identified. Of these, 119 underwent surgical pathology resection follow-up and demonstrated PTC. Approximately 75% of the cases were cytologically diagnosed as being positive for malignancy and these cases were associated with both the classic and tall cell variants of PTC at the time of resection, a greater likelihood of extrathyroidal extension, and the V600E type of BRAF mutation. In contrast, BRAF-mutated cases with diagnoses of atypia of undetermined significance/follicular lesion of undetermined significance (AUS/FLUS) and follicular neoplasm/suspicious for follicular neoplasm were found to be more strongly associated with the follicular variant of PTC, a K601E BRAF mutation, and a lower likelihood of extrathyroidal extension. However, a subset of AUS/FLUS cases with the V600E BRAF mutation appeared to represent sampling variability of the classic or tall cell variants of PTC. Bethesda thyroid diagnoses in the setting of a BRAF mutation reflect differences in PTC subtypes, the nature of cytology specimens, and molecular characteristics.

Ohori NP ，Singhal R ，Nikiforova MN ，Yip L ，Schoedel KE ，Coyne C ，McCoy KL ，LeBeau SO ，Hodak SP ，Carty SE ，Nikiforov YE ... -  《-》