Extraskeletal osteosarcoma: MDM2 and H3K27me3 analysis of 19 cases suggest disease heterogeneity.

We demonstrate that ESOS may include at least two small subsets: an MDM2-amplified deep soft-tissue ESOS (which may be related to DDLPS) and an H3K27me3-deficient organ-based ESOS (which is probably unrelated to MPNST). Larger studies are required to validate the present observations and investigate the clinical implications of such subcategorisation.