Clinical findings:
(1) affects the elderly
(2) slight male predominance
(3) hepatosplenomegaly may be present
Diagnostic features:
(1) peripheral blood leukocytosis due to increased numbers of mature and immature neutrophils
(2) prominent dysgranulopoiesis (acquired Pelger-Huet anomaly, abnormally condensed nuclear chromatin, bizarrely segmented nuclei, abnormal cytoplasmic granularity)
(3) fewer than 20% blasts in the peripheral blood
(4) fewer than 20% blasts in the bone marrow
(5) monocytes < 10% of WBC differential count; no or minimal absolute monocytosis (while not specified, the absolute count probably should be < 1,000 per µL)
(6) basophils < 2% of WBC differential count; no or minimal absolute basophilia
(7) neutrophil precursors (promyelocytes, myelocytes, metamyelocytes) >= 10% of WBC differential count
(8) hypercellular bone marrow with granulocytic proliferation and granulocytic dysplasia with or without dysplasia in the erythroid and megakaryocytic lineages (multilineage dysplasia may or may not be present)
Exclusions:
(1) presence of Philadelphia chromosome excludes
(2) presence of BCR/abl fusion gene excludes
(3) blasts >= 20% in peripheral blood or bone marrow (indicates AML)
Differential diagnosis:
(1) administration of granulocyte colony stimulating factor to a patient with myelodysplasia
Prognosis:
(1) median survival is less than 20 months
(2) thrombocytopenia and marked anemia are poor prognostic findings
(3) about a third progress to acute leukemia
