LAG3 and neoplasm: Dissection of more than 150–000 tumour- and immune-cell transcriptomes has uncovered follicular-like, partial EMT-like and dedifferentiated thyrocyte states embedded within ‘hot’ (CD8hi IFN-γhi), ‘cold’ (CD8lo) and ‘excluded’ (stroma-walled) immune niches; these phenotypes correlate with PD-1/LAG-3 expression, macrophage polarisation and radio-iodine refractoriness.