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WHO Classification of Tumours
Myelodysplastic/myeloproliferative neoplasm, unclassifiable
Tumours of haematopoietic and lymphoid tissues


Myelodysplastic/myeloproliferative neoplasm, unclassifiable, (MDS/MPN, U) meets the criteria for the MDS/MPN category in that, at the time of initial presentation, there are clinical, laboratory and morphological features that overlap both MDS and MPN. Cases classified as MDS/MPN, U do not meet the criteria for chronic myelomonocytic leukaemia , juvenile myelomonocytic leukaemia or atypical chronic myeloid leukaemia, BCR-ABL1 negative . The finding of a BCR-ABL1 fusion gene or of rearrangement of PDGFRA, PDGFRB or FGFR1 excludes the diagnosis of MDS/MPN, U.

It is important that the designation MDS/MPN, U not be used for patients with a previous, well-defined MPN who develop dysplastic features in association with transformation to a more aggressive phase. However, MDS/MPN, U may include some patients in whom the chronic phase of an MPN was not previously detected, and who initially present in transformation with myelodysplastic features. If the underlying MPN cannot be identified, the designation of MDS/MPN, U is appropriate. If there has been any recent cytotoxic or growth factor therapy, follow-up clinical and laboratory observations are essential to demonstrate that the peripheral blood (PB) and bone marrow (BM) changes are not due to the treatment.

> Related Topics
Myeloproliferative neoplasm, unclassifiable
Overview: Myelodysplastic syndromes/neoplasms
Introduction: Myeloid Neoplasms

Diagnostic criteria for MDS/MPN, U
Diagnostic criteria for MDS/MPN, U