Diagnostic Criteria and Classification of Myelodysplastic Syndromes

Abstract

A classification for myelodysplastic syndromes (MDS) has been proposed by several working groups and the World Health Organization (WHO). The recently updated criteria of the WHO are useful for discriminating MDS variants from each other. Moreover, minimal diagnostic criteria for MDS have been defined. In a few patients with unexplained cytopenia or dysplasia these criteria are not met. For these patients, the terms idiopathic cytopenia of unknown significance (ICUS) and idiopathic dysplasia of unknown significance (IDUS) have been proposed. Both conditions may progress to overt MDS over time. Therefore, once diagnosed, these patients should have a hematologic follow up. The final diagnosis of MDS has to be based on defined criteria and exclusion of all other causes of cytopenia and dysplasia, which requires detailed and sometimes extensive investigations, including a bone marrow biopsy, immunohistochemical studies, cytogenetic analysis, molecular studies, and flow cytometry. A diagnostic challenge is the potential co-existence of two myeloid neoplasms producing cytopenia or/and dysplasia in one patient. Once diagnosed, patients with MDS should be classified according to FAB and WHO criteria, and their risk concerning survival and AML evolution should be estimated by employing patient-related and disease-related risk factors, and established scoring systems, including the IPSS and/or WPSS, both of which are global standard.