Fig. 2

Morphological and genetic phenotypes of the lateral lymph node metastases. All stains are hematoxylin–eosin. A Approximately 1 mm large subcapsular deposit of metastatic papillary thyroid carcinoma (PTC). This lesion exhibited PTC related nuclear changes and was positive for BRAF1. B Low-power image of the 15 mm large deposit of follicular-patterned cells in a separate lateral node, consistent with metastatic follicular thyroid carcinoma (FTC). C High-power magnification reveals a microfollicular growth pattern and monotonous appearance, with nuclei clearly lacking PTC associated findings. D Schematic overview of the histological and molecular findings. The thyroid lobe is presented in grey, with the red tumor representative of the tall cell variant PTC found in the right lobe, with synchronous spread to central and lateral lymph nodes. These lesions were positive for BRAF1, the V600 specific antibody used to identify BRAF V600 mutated cases. The 12 mm minimally invasive FTC is depicted as a blue tumor, with spread to a lateral lymph node. These lesions exhibited an NRAS mutation detected by next-generation sequencing. Created using BioRender.com