“Mixed” MPNs are extremely rare and correspond to two entities of MPNs that occur in the same patient. For example, CML and ET, or PV, or erythrocytosis, or PMF, or two classical MPNs due to co-occurrence of somatic phenotypic genetic abnormalities (BCR-ABL1, JAK2 V617F, CALR m, JAK2 exon 12, and MPL m).