Intratumoural heterogeneous MNA (hetMNA) refers to the coexistence of MNA cells as a cluster (focus) or as single scattered cells and non-MYCN-amplified (nonMNA) tumour cells; in addition, tumour cells with MYCN gain (MNG, for definitions, see Materials and methods) can be present.13–29 HetMNA, thus far reported infrequently, can occur spatially within the tumour as well as between tumour and metastasis at the same time point15,20,22,24,25,27,28 or temporally during disease course.14,15,17,19–21,24,26–29. Here, MYCN is linked to neoplasm.