Morphological features that can predict BRAF -mutated carcinoma in paediatric thyroid cytology.

Objective: BRAF represents the most common diagnostic marker in papillary thyroid carcinoma (PTC). A few papers have demonstrated the correlation between BRAF and specific morphological findings on PTCs in the adult population. This is the first reported series investigating cytological morphological parameters in paediatric thyroid carcinoma.

Methods: One hundred and nineteen paediatric samples (56 male and 63 female patients), diagnosed in the period between April 2013 and July 2015, were enrolled in the study. Fifteen patients with inadequate results were excluded. Cytological cases were processed with liquid-based cytology (LBC). BRAF and immunocytochemistry for the VE1 antibody were performed on LBC.

Results: The diagnostic series included 10 mutated and 94 wild-type (WT) cases. Twenty two percent surgical samples showed 96% cytohistological concordance. The morphological analysis revealed plump cells (abundant eosinophilic cytoplasm and PTC nuclei) in all 10 mutated cases with only four cases showing a focal (less than 20% of the cells) plump component. None of the WT showed plump cells. A sickle nuclear shape was seen only in the mutated cases. VE1 yielded 100% positivity on mutated cases with three cytohistological discrepancies.

Conclusions: The BRAF mutation is also seen in paediatric cytology and the morphological features showed a high accuracy as both predictive mutational parameters and a helpful aid in management mainly of the aggressive BRAF mutated carcinomas.