Myelodysplastic Syndromes (MDS)

Question 1

What are myelodysplastic syndromes?

Answer 1

• 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*

Question 2

What are the classifications of MDS?

Answer 2

• 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*

Question 3

What is the common presentation of MDS?

Answer 3

• primarily older adults (mean age 70)
• 50% asymptomatic
• when symptomatic, related to pancytopenia (weakness, infection, and hemorrhage)

Question 4

What are possible histologic features of MDS?

Answer 4

• 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

Question 5

What is the course/prognosis of MDS?

Answer 5

-somewhat aggressive course, worse in t-MDS

-variable prognosis (median survival 9-29 mo), improves with younger age

-10-40% progress to AML