Minimal diagnostic criteria for myelodysplastic syndromes and separation from ICUS and IDUS: update and open questions.

Although a classification for myelodysplastic syndromes (MDS) has been proposed by several working groups and by the World Health Organization (WHO), with criteria useful to discriminate between disease variants, the important issue of minimal diagnostic criteria of MDS has only recently been addressed. In the current article, proposed minimal diagnostic criteria for MDS are discussed together with two conditions that do not meet these criteria, although cytopenia or dysplasia is present. These two conditions, idiopathic cytopenia of unknown significance and idiopathic dysplasia of unknown significance should be kept in mind as a provisional (potential) diagnosis in patients with suspected MDS. Both conditions can progress to frank MDS over time. Therefore, once diagnosed, these patients should have a haematological follow-up. The diagnosis MDS, on the other hand, needs to be based on robust criteria and exclusion of all other causes of cytopenia and dysplasia, which requires detailed and sometimes extensive investigations, including a bone marrow biopsy, cytogenetic analyses, molecular studies and flow cytometry.