Myelodysplastic Information and Courses from MediaLab, Inc.

The following pages in this presentation includes a series of white blood cell abnormalities that may be identified in a peripheral blood smear. Many of the cases will simulate the practice of a peripheral smear review by a hematology morphologist. He/she must asses what responses in patient care may be triggered by the clinician attempting to interpret the reported findings on a peripheral smearObservations of white blood cell abnormalities in the peripheral blood smear should be reported so as to direct the physician to an immediate specific diagnosis, such as: (1) atypical lymphocytes suggesting infectious mononucleosis rather than leukemia, (2) toxic granules in neutrophils as in acute infections, or atypical granules suggesting a genetic disorder, (3) an unusual mix of cells, such as too many or too few neutrophils, monocytes, or other myeloid cells, and (4) the presence of giant platelets, myelocytes, or other cells suggesting a myelodysplastic syndrome.In summary, laboratory data should be presented to clinicians in a user friendly way to promote effective decision making. The design of the data base of information must be directed toward providing clinically helpful information clearly and quickly in order to facilitate appropriate action in terms of optimizing patient care outcomes.d

A basophil and a small lymphocyte are compared in the same field of the upper photograph, A single basophil is shown in the lower photograph.The cytoplasmic granules of the basophil are larger than the granules of toxic granulation.They contain chemical mediators of immediate hypersensitivity, and are found in the cytoplasm and overlying the nucleus (better seen in the lower photograph). Basophilic granules stain metachromatically with toluidine blue indicating the presence of acid mucopolysaccharide or proteoglycans, both thought to be heparin or heparin-like substances.Basophils are related to tissue mast cells, each involved in hypersensitivity responses and following anaphylactic episodes.Under the stimulation of complement components C3a and C5a, many mediators are released from the basophil granules, including histamine, heparin, and eosinophil chemotactic factors of anaphylaxis, or ECF-A.Basophils are the least common neutrophils in the peripheral blood, comprising 2% or less of the differential count.The presence of large granules of irregular size in basophils and the admixture of eosinophilic granules may indicate dysplastic changes associated with myelodysplastic disorders and leukemia.