Refractory Anemia with Ring Sideroblasts

Supplemental Studies

Cytogenetic abnormalities are identified in fewer (about 10%) RARS patients than in other MDS
- Presence important for prognosis
If >450x10³/μL platelets in peripheral blood with marrow megakaryocytic proliferation, consider JAK2V617F

FISH for MDS associated abnormalities is not indicated for screening but is helpful if <20 metaphases were examined on karyotyping
In the setting of persistent cytopenia in the absence of definitive morphologic features of MDS:
- The following abnormalities are considered presumptive evidence of MDS
  - Deletions
    - -5, del(5q)
    - -7, del(7q)
    - del(9q)
    - del(11q)
    - del(12p)
    - t(12p)
    - -13, del(13q)
    - i(17q), t(17p)
    - idic(X)(q13)
  - Translocations
    - t(1;3)(p36.3;q21.2)
    - t(2;11)(p21;q23)
    - t(3;21)(q26.2;q22.1)
    - inv(3)(q21q26.2) and t(6;9)(p23;q24)
      - Most frequently present as AML and need to be closely monitored for overt transformation
    - t(11;16)(q23;p13.3)
- The following are commonly found in MDS but are not by themselves considered definitional for MDS
  - +8
  - -Y
  - del(20q)

Often shows decreased hematogones
May show immunophenotypic abnormalities
- e.g. CD56 on blasts and monocytes
Paroxysmal Nocturnal Hemoglobinuria clone may be present, particularly in RCUD
- CD55 and CD59 deficient RBC

CD34+ blast clusters
- ≥3 clusters of ≥3 cells each
- Confers worse prognosis in MDS with <5% blasts

Dense, diffuse fibrosis confers worse prognosis independent of IPSS
- Grade 2-3 per the European consensus scale (Thiele 2005)