Myelodysplastic Syndrome (MDS)
Diagnosis

Updated: October 2010

Diagnosis

Myelodysplastic syndrome (MDS) is a clonal stem cell disorder characterized by low blood counts despite a bone marrow that is usually quite cellular. However, the cells within the bone marrow have an abnormal (“dysplastic”) appearance and frequently are dysfunctional. MDS has a tendency to develop into cancer of the bone marrow (acute leukemia or “AML”) although the speed with which this occurs in MDS is highly variable. Furthermore, patients with MDS may have separate medical problems that have a more significant impact on their quality and duration of life.

Investigations

Patients with low blood counts should have the following performed:

• Creatinine, electrolytes and liver function testing (including LDH)

• Serum ferritin

• B₁₂ and folate levels

• Reticulocyte count

• Serum TSH

If no explanation is found for low counts, referral to a hematologist is recommended for:

• Bone marrow aspirate and biopsy - SENDING A MARROW SAMPLE FOR CYTOGENETIC ANALYSIS IS CRITICAL IN MDS

• Peripheral blood flow cytometry for paroxysmal nocturnal hemoglobinuria (“PNH”) testing

Patients with either unexplained hematologic cytopenias or documented MDS can be referred to the Marrow Failure Syndromes Clinic at Vancouver General Hospital by sending information by fax to 604-875-4763.

Classification

MDS is currently classified according to the World Health Organization Classification of Hematopoietic and Lymphoid Tumours (2008)¹ in the following manner:

Myelodysplastic syndromes

• Refractory cytopenia with unilineage dysplasia (RCUD)

• Refractory anemia with ring sideroblasts (RARS)

• Refractory cytopenia with multilineage dysplasia (RCMD)

• Refractory anemia with excess blasts (RAEB-1/2)

• MDS with isolated deletion of 5q

• MDS, unclassifiable

• Refractory cytopenia of childhood

Myelodysplastic/Myeloproliferative neoplasms

• Chronic myelomonocytic leukemia (CMML-1/2)

• Atypical chronic myeloid leukemia

• Juvenile myelomonocytic leukemia (JMML)

• MDS/MPD neoplasm, unclassifiable.

Prognosis

Three key characteristics are most predictive of prognosis in MDS:

1. Number of low blood counts (hemoglobin, WBC and platelets)

2. Percentage of immature (“blast”) cells in the bone marrow

3. Bone marrow cytogenetic analysis (karyotype)

These factors are “scored” according to the IPSS² shown below.

International Prognostic Scoring System ("IPSS"; Greenberg, 1997)

		SCORE
Number of Cytopenias  [Hb<100, ANC<1.5, Plt<100]	0-1 2-3	0 0.5
Marrow blast count	5-10% 11-20% >20%	0.5 1.0 1.5
Cytogenetics	Good  [Normal; -Y, del 5q or 20q alone]	0
	Intermediate  [All non-good, non-poor]	0.5
	Poor  [Abnormality of chromosome 7, ≥3 unassociated abnormalities	1.0

Score from each of the three categories are added together to arrive at an overall IPSS score (see table below), associated with a distinct prognosis.

Risk Category	Score	Median Survival (yrs)
LOW	0	5.7
INT-1	0.5-1.0	3.5
INT-2	1.5-2.0	1.2
HIGH	≥2.5	0.4

The information contained in these guidelines is a statement of consensus of Leukemia/BMT Program of BC professionals regarding their views of currently accepted approaches to treatment. Any clinician seeking to apply or consult these documents is expected to use independent medical judgment in the context of individual clinical circumstances to determine any patient’s care or treatment. Use of these guidelines and documents is at your own risk and is subject to the Leukemia/BMT Program of BC’s terms of use available at Terms of Use.