Unraveling myeloma heterogeneity: from nanometers to kilometers. Spatial transcriptomics is a powerful and promising technique that enables the study of myeloma and its microenvironment at the micrometer scale. However, a comprehensive understanding of myeloma biology requires consideration of additional layers of complexity. These include geographical differences in disease incidence (kilometer scale), interpatient heterogeneity such as molecular subgroups (meter scale), distinct growth patterns and local disease distribution within and beyond the skeletal system, including diffuse infiltration, as well as extra- and paramedullary manifestations (centimeter scale), and variation in surface molecule expression among individual tumor cells (nanometer scale). The figure was prepared by Emilia Stanojkovska.