Myelodysplastic syndrome

Big picture

Myelodysplastic syndrome (MDS) is a clonal stem-cell disorder of the bone marrow where the marrow is usually cellular, but blood production is ineffective and dysplastic. The result is the classic paradox:

hypercellular/dysplastic marrow → peripheral cytopenia.

For the exam, think of MDS in an older patient with unexplained macrocytic anemia, often with neutropenia and/or thrombocytopenia, a low reticulocyte count, and abnormal cells on smear. The major danger is progression to acute myeloid leukemia (AML).

The textbook emphasizes that MDS is a heterogeneous clonal hematopoietic stem-cell disorder with dysplasia in one or more cell lines, peripheral cytopenia due to ineffective hematopoiesis, and AML risk that increases with higher myeloblast percentage.

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