JMML represents the most common myeloproliferative syndrome observed in young children.

Other chronic myeloproliferative syndromes such as polycythemia vera and essential thrombocytosis are extremely rare in children.

Ph1-negative CML is a poorly defined entity that is less clearly distinguished from other myeloproliferative syndromes.

AML must be carefully differentiated from "preleukemic" conditions such as myelodysplastic or myeloproliferative syndromes, which are treated differently.

Patients with "preleukemic" conditions, such as myelodysplastic syndromes or myeloproliferative syndromes, who develop a chloroma are often treated as if they have transformed to acute leukemia.

They can be seen in the leukemic blasts of M2 and M3 acute myeloid leukemia and in high grade myelodysplastic syndromes and myeloproliferative syndromes.

O'Donnell MR, Nademanee AP, Snyder DS, et al.: Bone marrow transplantation for myelodysplastic and myeloproliferative syndromes.

Michaux JL, Martiat P: Chronic myelomonocytic leukaemia (CMML)--a myelodysplastic or myeloproliferative syndrome?

The overproduction of red blood cells may be due to a primary process in the bone marrow (a so-called myeloproliferative syndrome), or it may be a reaction to chronically Hypoxia (medical) or, rarely, a malignancy.