Diagnostic value, three-dimensional inference, and relationship with BRAF V600E of both papillary fragments and cellular swirls in fine-needle aspiration cells of patients with conventional papillary thyroid carcinoma

Objectives: The two characteristic architectural patterns of conventional papillary thyroid carcinoma (PTC) are papillary fragments and cellular swirls. However, the diagnostic value, three-dimensional inference, and relationship with BRAF V600E of these two architectural patterns are currently unclear. Materials and Methods: For the present study, a retrospective analysis was carried out on 343 cases of conventional PTC, where the diagnosis of all cases was verified by post-operative histopathological assessment. Furthermore, 200 patients with benign thyroid lesions were randomly sampled and included in the research to form the control cohort. Results: When interpreting conventional PTC based on the papillary fragments and cellular swirls, their specificity for both is 100%, while using combinations of papillary fragments and cellular swirls by parallel tests to interpret conventional PTC, the sensitivity is 53.94%. On careful observation and analysis, we propose that a papillary architecture is centered around a fibrovascular core, with a possible cellular swirl at the top, and tumor cells enveloping the peripheral regions. The reason why histopathology did not find cellular swirls may be that cellular swirls are part of the papillary architecture, and two-dimensional tissue sections cannot display isolated and typical cellular swirls. This study also showed that the unique swirl-fiber architecture was only present in the BRAF V600E-negative group ( P <0.001). Conclusion: Both papillary fragments and cellular swirls, whether typical or atypical, hold significant clinical value for the interpretation of conventional PTC; the swirl-fiber architecture may have important clinical diagnostic value to interpret conventional PTC with negative BRAF V600E.