TriangleHEALTH PROFESSIONAL · SOURCE READING
Disease Overview
Source: Myelodysplastic/Myeloproliferative Neoplasms Treatment (PDQ®)–Health Professional Version, National Cancer Institute.
Source updated: May 14, 2025 · Captured 2026-09-09.
Selected source text with whitespace normalised. This Triangle page is not an NCI PDQ summary.
Context: Treatment of MDS/MPN, Unclassifiable
Myelodysplastic/myeloproliferative neoplasm, unclassifiable (MDS/MPN-UC) (also known as mixed myeloproliferative/myelodysplastic syndrome, unclassifiable and overlap syndrome, unclassifiable) shows features of both myeloproliferative disease and myelodysplastic disease but does not meet the criteria for any of the other MDS/MPN entities.[1]
Source links and citations
Diagnostic criteria for MDS/MPN-UC can be either:[1]
Source links and citations
The combination of four sets of criteria (a–d):
The combination of four sets of criteria (a–d):
Clinical, laboratory, and morphological features of myelodysplastic syndrome (MDS) (e.g., refractory anemia, refractory anemia with ringed sideroblasts, refractory cytopenia with multilineage dysplasia, and refractory anemia with excess of blasts) with fewer than 20% blasts in the blood and bone marrow. For more information on anemia, see Fatigue.
Source links and citations
The combination of four sets of criteria (a–d):
Prominent myeloproliferative features, e.g. platelet count greater than 600 × 109/L associated with megakaryocytic proliferation, or white blood cell count greater than 13.0 × 109/L with or without splenomegaly.
The combination of four sets of criteria (a–d):
No history of an underlying chronic myeloproliferative disorder (CMPD), MDS, or recent cytotoxic or growth factor therapy that could cause the myelodysplastic or myeloproliferative features.
The combination of four sets of criteria (a–d):
No Philadelphia chromosome or BCR::ABL1 gene fusion, del(5q), t(3;3)(q21;q26), or inv(3)(q21q26).
Mixed myeloproliferative and myelodysplastic features that cannot be assigned to any other category of MDS, CMPD, or MDS/MPN.
Clinical characteristics of MDS/MPN-UC include:
Features of both MDS and CMPD.
Hepatomegaly.
Splenomegaly.
The incidence and etiology of MDS/MPN-UC are unknown.
Laboratory features typically include anemia and dimorphic erythrocytes on the peripheral blood smear.[1] Thrombocytosis (platelet count >600 × 109/L) or leukocytosis (white blood cell count >13 × 109/L) are present. Neutrophils may exhibit dysplastic features, and giant or hypogranular platelets may be present. Blasts make up less than 20% of the white blood cells and of the nucleated cells of the bone marrow. The bone marrow is hypercellular and may exhibit proliferation in any or all of the myeloid lineages. Dysplastic features are present in at least one cell line.[1]
No cytogenetic or molecular findings are available that are specific for MDS/MPN-UC. In one small series, six of nine patients (those with ringed sideroblasts associated with marked thrombocytosis [RARS-T]) had JAK2 V617F variants, which caused constitutive activation of the JAK2 tyrosine kinase. This JAK2 pathogenic variant is also commonly observed in patients with polycythemia vera, essential thrombocythemia, and idiopathic myelofibrosis.[2] Because of its rare occurrence, the prognosis and predictive factors are unknown.[1]
Publication references
Read the original reference and check its publication notices.
Preserved source evidence · Not medical advice