Myelodysplastic/myeloproliferative neoplasms (MDS/MPN) share characteristics of both MDS and MPN, and  often show a hypercellular bone marrow. The main types of MDS/MPN include chronic myelomonocytic leukemia (CMML), juvenile myelomonocytic leukemia (JMML), atypical chronic myeloid leukemia (aCML), while a small number of patients do not fall in any of the three categories and are therefore unclassifiable (MDS/MPN-U).