5q- Syndrome

Definition

Myelodysplastic syndrome characterized by deletion of 5q as the sole cytogenetic abnormality and no increase in blasts

Deletion of 5q is sole cytogenetic abnormality
- Additional molecular abnormalities may be present
  - 5-10% have JAK2V16F mutation
- Loss of Y is allowed (normal age related phenomenon)
Peripheral blood blasts <1%, based on 200 leukocyte differential
- If blood blasts = 1%, designate as MDS-U
- If blood blasts = 2-4%, or Auer rods present, designate as Refractory Anemia with Excess Blasts (RAEB)
Bone marrow blasts <5%, based on 500 nucleated cell differential
- If marrow blasts 5-19%, or Auer rods present, designate as RAEB
  - Poor prognosis
Bone marrow megakaryocytic hyperplasia
- Hypolobated or unilobated, small megakaryocytes
  - Increased in number
  - May loosely cluster
- Normal or increased platelet count
  - Frequently abnormal morphology
Macrocytic anemia is usually present
- Often with bone marrow erythroid hypoplasia and megaloblastoid differentiation
  - Dyssynchronous maturation of nucleus and cytoplasm of erythroid precursors
Dysgranulopoeisis when present may be associated with inferior survival