Establishing A Diagnosis

The diagnosis of MDS in most patients is readily established with standardized testing, which should include history and physical examination, complete blood count, and review of the peripheral blood smear. The findings of cytopenias in the absence of explanation from biochemical, vitamin deficiency, hemorrhage, toxin/drug, or infectious etiology should lead to a bone marrow aspirate and biopsy with routine cytogenetic evaluation. The diagnosis of MDS is based primarily on morphologic criteria demonstrating dysmorphic features in the peripheral blood and bone marrow precursors (described above and Table 39.1). Although some of the classification systems include cytogenetic information (IE:WHO), they are based primarily on bone marrow and peripheral blood morphology. A diagnosis of MDS cannot be definitively established without examination of a bone marrow aspirate. Peripheral blood smears may be suggestive, but not conclusive. Some in the hematologic community believe a bone marrow smear alone is adequate for diagnosis. In some instances a smear is sufficient, however, a bone marrow biopsy provides complimentary information on cellularity, infiltrative disease, megakaryocyte morphology, and fibrosis that is often important in completing the evaluation and is informative for thera peutic decisions. Analysis of the marrow population, using flow cytometric analysis has become standard for the diagnosis and subtyping in patients with acute leukemia. It is more routinely being applied to establish a diagnosis of MDS, as well. Abnormal populations and skewed antigen expression can be identi-fied.52-58 However, comparative studies of bone marrow morphology and flow cytometry results have not been conducted, and thus one cannot be certain if used alone whether flow cytometry results can reliably establish a diagnosis and classification of MDS. Accurate classification according to FAB or WHO criteria must be based, at least in part, on bone marrow morphology. Thus, flow cytometry should be viewed as a complementary examination, but not sufficient to establish the diagnosis and classification.

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