Wallach's Interpretation of Diagnostic Tests: Pathways to Arriving at a Clinical Diagnosis (358 page)

   
Molecular genetic studies
reveal 30% higher abnormalities than classic karyotyping. The finding of recurrent molecular genetic alterations with prognostic and diagnostic impact indicates that in the near future, implementing comprehensive genetic studies will play an important role in clinical practice.

   
Serum B
₁₂
and folate
should be obtained to exclude deficiencies that may mimic MDS morphologically. The karyotype is normal in these deficiencies.

   
Hb electrophoresis
may reveal acquired Hb H disease, or rarely acquired thalassemic syndrome, but it is not necessary for the diagnosis of MDS.

   
Serum immunoglobulins
are variably abnormal, with hypogammaglobulinemia, polyclonal hypergammaglobulinemia, and even monoclonal gammopathies reported.

   Studies for PNH help differentiate the two diseases or reveal various combinations of PNH with aplastic anemia or refractory anemias as part of a MDS picture.

   
Serology for HIV infection
may be indicated in some cases, since AIDS may be associated with dysplastic hematopoiesis and cytopenias.

   Prognosis

   The International Prognosis Scoring System (IPSS) classifies MDS patients into four prognostic categories based on the number of cytopenias, cytogenetics, and percent of blasts in the bone marrow.

Suggested Readings

Abdel-Wahab O, Figueroa ME. Interpreting new molecular genetics in myelodysplastic syndromes.
Hematology Am Soc Hematol Educ Program.
2012;2012:56–64.

Brunning RD, Orazi A, Germing U, et al. Myelodysplastic syndromes/neoplasms, overview. In:
WHO Classification of Tumours of Haematopoietic and Lymphoid Tissues
, 4th ed. Lyon, France: International Agency for Research on Cancer; 2008:88–93.

Nimer SD. Myelodysplastic syndromes.
Blood.
2008;111:4841–4851.

Stone RM. How I treat patients with myelodysplastic syndromes.
Blood.
2009;113:6296–6303.

Tefferi A, Vardiman JW. Mechanisms of disease: myelodysplastic syndromes.
N Engl J Med.
2009;361:1872–1885.

CHRONIC MYELOMONOCYTIC LEUKEMIA (CMML)

   Definition

According to the 2008 WHO classification, CMML belongs to the group of myelodysplastic/myeloproliferative neoplasms. CMML is subdivided into two subcategories:

   CMML-1: blasts (including promonocytes) <5% in the peripheral blood and <10% in the bone marrow

   CMML-2: blasts (including promonocytes) 5–19% in the peripheral blood or 10–19% in the bone marrow or the presence of Auer rods