Investigating tumour heterogeneity in a melanoma arising in congenital melanocytic nevus using in situ spatial gene expression analysis

Melanoma is one of the most aggressive skin cancers with high mortality rates.1 It frequently exhibits high heterogeneity, with diverse genetic and phenotypic characteristics, which often complicate accurate diagnosis, classification and treatment planning.2 A previous study showed that melanoma tumours with high heterogeneity tend to exhibit reduced infiltration of antitumour immune cells, lower expression of immunomodulatory genes and poorer survival.3