What are myelodysplastic syndromes?
-dysplasia of myeloid cells
-bone marrow is hypercellular as poorly differentiated cells fail to enter periphery
-myeloblasts <20% prevalence in bone marrow (as opposed to >20% in AML)
-results in peripheral cytopenias
*10-40% progress to AML*
What are the classifications of MDS?
-refractory anemia (RA): <5% myeloblasts, abnormal RBC precursors
-refractory anemia with ring sideroblasts (RARS): <5% myeloblasts w/ >15% of RBC precursors as ring sideroblasts
-refractory anemia with excess blasts (RAEB): 5-19% myeloblasts
-refractory anemia with excess blasts in transformation (RAEB-T): 5-19% myeloblasts
-chronic myelomonocytic leukemia (CMML): <20% myeloblasts w/ 1x109 monocytes in peripheral blood
*all must be <20% otherwise they are classified as AML instead*
What is the common presentation of MDS?
-primarily older adults (mean age 70)
-when symptomatic, related to pancytopenia (weakness, infection, and hemorrhage)
What are possible histologic features of MDS?
-ring sideroblasts: erythroblasts with iron-laden mitochondira
-pseudo-Pleger-Hüet cells: neutrophils with only two lobes
-pawn ball megakaryocytes: megakaryocytes with single unlobulated nuclei or with multiple nuclei
What is the course/prognosis of MDS?
-somewhat aggressive course, worse in t-MDS
-variable prognosis (median survival 9-29 mo), improves with younger age
-10-40% progress to AML