Therefore, ancillary tests, such as DNA methylation profiling (in ensemble with the Heidelberg Sarcoma classifier25), CNV profiling or panel-based DNA sequencing may be helpful in correctly classifying a neoplasm as either one of the three classes of mesenchymal tumors with DICER1 alteration, or to exclude other DICER1-associated tumor entities, such as SLCT DICER1 or uterine MAS. Here, MAS1 is linked to mesenchymal cell neoplasm.