As mentioned previously, the patient had below-range WBCs, RBCs, and platelets, which is known as pancytopenia. Their RBCs were macrocytic, with the mean corpuscular volume well over the upper limit of 100 fl.
Two abnormal findings in the differential were 5% blasts and 1% myelocytes, two blood cell precursors not normally found in healthy peripheral blood.
The blasts are somewhat unexpected in patients with a low white blood cell count because they are usually associated with acute leukemias and high white cell counts. Also, the whole blood picture, except for the blasts, is that of pancytopenia seen in aplastic anemia.
However, the poikilocytosis, anisocytosis, macrocytosis, low counts in three cell lines, and immature red cells all point to Myelodysplastic Syndrome (MDS). MDS is a clonal myeloid disorder in which cells of myeloid origin, especially the erythrocytes, do not mature properly. This is known as ineffective and disordered erythropoiesis, leading to anemia and dysplastic red blood cells.
Because of the 5% blasts, the diagnosis is likely myelodysplastic syndrome with excess blasts (MDS-EB), formerly known as Refractory Anemia with Excess Blasts (RAEB). However, a bone marrow biopsy, aspirate, and chromosomal and molecular testing will definitively determine the diagnosis.
