Diagnostic Features of MDS

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The page below is a sample from the LabCE course Myelodysplastic Syndromes (MDS). Access the complete course and earn ASCLS P.A.C.E.-approved continuing education credits by subscribing online.

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Diagnostic Features of MDS

Diagnosis of MDS should be considered when patients have unexplained blood cytopenia, such as anemia, neutropenia, or thrombocytopenia (isolated or combined). Laboratory diagnosis of MDS should include:
  • Complete blood cell count and blood smear examination:
    • The complete blood cell count (CBC) may show anemia which is usually macrocytic or normocytic, neutropenia with dysplastic features, and/or thrombocytopenia. The platelets may be normal in shape, giant, or hypo-granular. A careful review of the CBC count and well-stained blood smears, along with the identification of any dysplasia present, are vitally important in evaluating cases of MDS.
  • Bone marrow aspirate and biopsy examination:
    • A well-stained bone marrow aspirate with Romanowsky (Wright-Giemsa) stain is very important in evaluating cases for MDS, as well as Hematoxylin and Eosin (H & E) stain of the core biopsy.
    • The bone marrow may show normal or hyper-cellularity with varying degrees of dysplasia within the three myeloid cell lines (dysgranulopoiesis, dyserythropoiesis, and/or dysmegakaryopoiesis). The percentage of bone marrow blasts measured during bone marrow aspirate/biopsy analysis typically ranges between normal (less than 5%) to increased (5%-19%), depending on the subtype of MDS.
    • An increased rate of apoptosis (degenerating cells) is a common MDS findings, and is a contributing factor to the presence of cytopenias.
  • Bone marrow cytogenetic examination:
    • Abnormal cytogenetics findings are observed in approximately 50% of MDS cases. According to the International Prognostic Scoring System (IPSS), MDS with 5(q) deletion chromosome has a decreased likelihood of developing into AML (good prognostic score). MDS with partial deletion of 11 (q) has an intermediate prognostic score. Deletion of 7 chromosome and trisomy 8 carry a poor diagnostic score (increased incidence of developing AML).
  • Bone marrow flow-cytometry:
    • May show normal or increased blast counts. Monoclonal antibodies that are reactive to blast cell surface markers are used to determine the number of blasts. Examples: CD-34, HLA-DR, and CD-117. Correlation between the blasts counted via differentials and flow-cytometry an important aspect of the MDS evaluation process.
  • Bone marrow biopsy immunohistochemistry stain:
    • CD-34 and CD-117 immunostain can be performed on the core biopsy. When the bone marrow aspirate is suboptimal, the core biopsy H&E stain, as well as the immunostains are very valuable in the evaluation process.
    • The number of bone marrow and peripheral blood blasts (normal or increased) determine the subtype and the classification of MDS, and also determine the prognosis and risk factors.
  • Blood iron, B12, and folic acid levels to rule out nutritional causes:
    • The anemia, neutropenia, and thrombocytopenia are not due to nutritional factors in cases of MDS. Iron study tests would be normal, as well as vitamin B12, and folate levels. These test are performed prior to evaluating the case as possible MDS.
  • Immunophenotyping:
    • There should be good correlation between the blasts determined by flow cytometry (antibody to CD-34+ or CD-117+ cells), immunohistochemistry (antibody to CD-34+ or CD-117+ cells), and Wright-Giemsa stained aspirate smears. In some cases, there is discordance between the three methods due to sample quality, bone marrow fibrosis, or hemodilution. In such cases, immunohistochemical stain on the biopsy section (antibody to CD34+ or CD-117+ cells) becomes very valuable in staining the blasts and determining the diagnosis.