Considering the negative prognostic value that increased levels of PMN-MDSCs specifically have in many tumors, such as for instance melanomas, colorectal cancers, and non-small cell lung cancers [30,31,34], the selective increase in this subset of MDSCs in PMF patients, besides playing a role in the chronic inflammatory status that characterizes the disease and/or in the migration of malignant CD34+ cells from the PB toward the spleen, could also be relevant for a prognostic stratification of the patients. This evidence concerns the gene CD34 and melanoma.