Diagnostic Value of BRAF (V600E) Mutation Analysis in Thyroid Fine Needle Aspiration Specimens in Indeterminate, Suspicious and Diagnostic Papillary Carcinoma. Our Institutional Experience in 45 Cases
Natalia Tallada, Javier Hernandez-Losa, Carles Zafon, Rosa Somoza, Margarita Alberola, Carmela Iglesias, Carme Dinares, Josep Castellvi, Jordi Mesa, Gabriel Obilos, Santiago Ramon y Cajal. Vall d'Hebron University Hospital, Barcelona, Spain
Background: Papillary thyroid carcinoma (PTC) is the most common cancer. The BRAF gene mutation is present in a significant number of cases of PTC and is predictive of some clinicopathological characteristics. Fine needle aspiration biopsy (FNAB) combined with molecular analysis provides great diagnostic accuracy and allows for selection for therapeutic decisions.
Design: Analysis of mutation status of BRAF (V600E) in samples from FNAB in the categories of indeterminate atypia, suspicious and diagnostic PTC.
BRAF (V600E) analysis was performed on FNAB material in 45 cases. 25 cases from retrospective follow-up patients and 20 prospective study (36 women / 9 men). Cytological diagnosis was: PC in 27/45 cases; suspicious for PC 8/45 cases; indeterminate 7/45 and benign 3/45 cases. Cytological diagnosis was confirmed by histology in 42 patients: 6 benign nodules and 32 classical variant of PC, 4 follicular variant. DNA was extracted and BRAF (V600E) mutation was detected by polymerase chain reaction followed by restriction enzyme digestion and sequencing of exon 15.
Results: BRAF (V600E) mutation was detected in 21 cases (46.6%), in 15 /21 with coincident previous diagnosis on cytology of PC and subsequent histology. 6 /21 cases were suspicious for malignancy in cytology and surgery was recommended. Definitive histological diagnosis of PC was established in all cases.Wild-type BRAF was detected in 24 cases (53.3%). No correlation was found in 12 cases (50%) with cytological and histological diagnoses of PC and wild-type BRAF, 4 patients had follicular variant of PC and in 3 of suspicious for malignancy and confirmed PC by histology. 2 cases of indeterminate atypia on cytology and wild –type BRAF had a benign final tissue diagnosis and 3 had PC. The absence of mutation was coincident with cytological diagnosis of benign nodules in 4 patients.
Conclusions: Prevalence of BRAF (V600E) mutation detected from FNAB specimens is 46.6% and all cases correlate with previous cytological and final histological diagnoses of PC. Wild–type BRAF is present in 53.3%, mutation was not detected in 4 cases of follicular variant. In problematical category of indeterminate atypia or suspicious, molecular analysis increase the accuracy of cytological evaluation and preoperative selection of patients.
Wednesday, March 21, 2012 1:00 PM
Poster Session VI # 53, Wednesday Afternoon