Are there specific cytologic features that can predict BRAF mutational status of papillary thyroid carcinoma in fine-needle aspiration specimens?

Background: BRAF mutation is the most common molecular alteration found in papillary thyroid carcinoma (PTC) and has been linked to recurrent disease or possibly more aggressive behavior. Some studies have reported sickle-shaped nuclei (SSN) and plump pink cells (PPC) to be predictive markers of BRAF mutation in FNA cytology. We aimed to evaluate the reproducibility of the aforementioned cytologic features.

Methods: A computerized search for diagnosed PTC surgical pathology cases tested for BRAF mutation by Sanger DNA sequencing was performed. Blinded to BRAF results, the corresponding cytology was reviewed for presence of SSN and PPC. Classic nuclear PTC (CNPTC) features, cystic change, and psammoma bodies were also evaluated. The results were correlated with BRAF mutational status and histologic subtypes.

Results: Study cohort consisted of 113 cases (74 BRAF mutated, 39 BRAF wild type). SSN and combined CNPTC /SSN had positive predictive value of 74% and 75%, respectively. CNPTC showed 92% sensitivity and 20% specificity. Psammoma bodies had 92% specificity and 5% sensitivity. The presence of combined PPC/SSN showed 80% specificity, 27% sensitivity, and diagnostic accuracy of 45%. CNPTC was seen in 60/61 (98%) SSN and 45/45 (100%) PPC. There was no significant statistical association between SSN, PPC, and CNPTC with specific histologic subtypes and BRAF mutational status.

Conclusion: CNPTC is sensitive but not specific for BRAF mutational status. SSN, PPC, and CNPTC are not predictive markers for the presence of BRAF mutation or histologic subtypes. Additional studies may be needed to further corroborate these findings.