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Objectives Few cytologically indeterminate thyroid fine-needle aspirations (FNAs) harbor BRAF V600E. Here, we assess interobserver agreement for The Bethesda System for Reporting Thyroid Cytopathology (TBSRTC) category III (atypia of undetermined significance [AUS]) FNAs harboring BRAF V600E and contrast their features with those harboring non- BRAF V600E alterations, with attention to cytopathology experience. Methods Seven reviewers evaluated 5 AUS thyroid FNAs harboring BRAF V600E. To blind reviewers, cases were intermixed with 19 FNAs falling within other TBSRTC categories and in which genetic alterations other than BRAF V600E had been identified (24 FNAs total). Interobserver agreement against both "index" and most popular ("mode") diagnoses was calculated. Four additional BRAF V600E cases were independently reviewed. Results Reviewers included 3 trainees and 3 American Board of Pathology (board)–certified cytopathologists. Board-certified cytopathologists, whose experience ranged from 2 to more than 15 subspecialty practice years, had known AUS rates. BRAF V600E was identified in 5 of 260 (2%) AUS FNAs. Interobserver agreement was higher among cytopathologists with more experience. Mode diagnosis differed from index diagnosis in 6 of 11 cases harboring RAS-like alterations; mode diagnosis was AUS in 4 of 5 BRAF V600E FNAs. Conclusions Atypia of undetermined significance of thyroid FNAs harboring BRAF V600E is uncommon yet relatively reproducible, particularly among pathologists with experience. It is advisable to sequence BRAF across V600 in such cases. [ABSTRACT FROM AUTHOR]

Background and Aim: A recently carried out randomized controlled trial showed the benefit of a novel 20‐G fine‐needle biopsy (FNB) over a 25‐G fine‐needle aspiration (FNA) needle. The current study evaluated the reproducibility of these findings among expert academic and non‐academic pathologists. Methods: This study was a side‐study of the ASPRO (ASpiration versus PROcore) study. Five centers retrieved 74 (59%) consecutive FNB and 51 (41%) FNA samples from the ASPRO study according to randomization; 64 (51%) pancreatic and 61 (49%) lymph node specimens. Samples were re‐reviewed by five expert academic and five non‐academic pathologists and rated in terms of sample quality and diagnosis. Ratings were compared between needles, expert academic and non‐academic pathologists, target lesions, and cytology versus histological specimens. Results: Besides a higher diagnostic accuracy, FNB also provided for a better agreement on diagnosing malignancy (ĸ = 0.59 vs ĸ = 0.76, P < 0.001) and classification according to Bethesda (ĸ = 0.45 vs ĸ = 0.61, P < 0.001). This equally applied for expert academic and non‐academic pathologists and for pancreatic and lymph node specimens. Sample quality was also rated higher for FNB, but agreement ranged from poor (ĸ = 0.04) to fair (ĸ = 0.55). Histology provided better agreement than cytology, but only when a core specimen was obtained with FNB (P = 0.004 vs P = 0.432). Conclusion: This study shows that the 20‐G FNB outperforms the 25‐G FNA needle in terms of diagnostic agreement, independent of the background and experience of the pathologist. This endorses use of the 20‐G FNB needle in both expert and lower volume EUS centers. [ABSTRACT FROM AUTHOR]