Hematologic Complications of Myelodysplastic Syndromes (MDS)

Table of Contents

1. Myelodysplastic Syndromes (MDS)

Myelodysplastic syndromes (MDS) refer to a group of hematologic malignancies characterized by dysplastic cell maturation and isolated or multiple cytopenias (anemia, neutropenia, thrombocytopenia)
MDS shares clinical and pathological features with acute myeloid leukemia (AML), but the proportion of blasts in peripheral blood and bone marrow is lower in MDS (<20% by definition)
As a result, patients with MDS are at risk for symptomatic anemia, infections, bleeding, varying degrees of bone marrow failure, and progression to AML
The majority of morbidity and mortality in MDS is due to complications from cytopenias rather than transformation to AML

More than 75% of MDS patients develop anemia, with half having hemoglobin (Hb) levels below 10 g/dL.
Anemia may present with symptoms such as fatigue, anorexia, weight loss, angina, dizziness, dyspnea, headache, and cognitive impairment.
Causes of anemia should be evaluated, including blood loss, hemolysis, renal failure, medications, nutritional deficiencies, thyroid dysfunction, autoimmune diseases, and anemia of chronic disease.
Diagnostic workup includes:
- Complete blood count (CBC), peripheral blood smear, reticulocyte count, and reticulocyte production index (RPI) calculation.
- Evaluation of renal and thyroid function, serum iron, transferrin, ferritin, folate, vitamin B12, copper, and erythropoietin (EPO) levels.

For symptomatic patients, treatment is based on MDS risk category, RBC production level (RPI), and serum EPO levels.

Low/very low/intermediate risk MDS (IPSS-R ≤4.5 points)
- If RPI <2 and serum EPO ≤500 mU/mL → Initial treatment with erythropoiesis-stimulating agents (ESAs) is recommended.
- If RPI ≥2 or serum EPO >500 mU/mL → RBC transfusion or ESA with/without myeloid growth factors may be considered.
High/very high-risk MDS (IPSS-R >4.5 points)
- Chronic transfusion therapy alongside definitive treatment of the underlying disease is suggested.
- Correction of contributing factors (e.g., bleeding, hemolysis) is necessary.
During transfusion, leukoreduced blood products are recommended to reduce the risk of alloimmunization, febrile transfusion reactions, cytomegalovirus (CMV) and other viral infections, and immunosuppression.

Infection is a major cause of morbidity and mortality in MDS patients.
Increased infection risk is associated with neutropenia and granulocyte dysfunction.
Bacterial infections, particularly those involving the skin, are common.
Neutropenic patients (absolute neutrophil count <500/microL) require urgent evaluation, blood cultures, and immediate empiric antibiotic therapy.

Bleeding in MDS may result from thrombocytopenia, qualitative platelet dysfunction, or coagulation disorders.
Platelet transfusion recommendations:
- Prophylactic transfusion for asymptomatic patients with platelet counts <10,000/microL
- Higher threshold for patients with active bleeding, fever, severe infection, pulmonary dysfunction, coagulopathy, or CNS abnormalities.